diff --git a/aiohttp/client.py b/aiohttp/client.py
index e7d3570dced..c21ce173cf2 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -222,7 +222,7 @@ def __init__(
         trust_env: bool = False,
         requote_redirect_url: bool = True,
         trace_configs: Optional[List[TraceConfig]] = None,
-        read_bufsize: int = 2 ** 16
+        read_bufsize: int = 2 ** 16,
     ) -> None:
 
         if loop is None:
@@ -336,7 +336,7 @@ def __del__(self, _warnings: Any = warnings) -> None:
             else:
                 kwargs = {}
             _warnings.warn(
-                "Unclosed client session {!r}".format(self), ResourceWarning, **kwargs
+                f"Unclosed client session {self!r}", ResourceWarning, **kwargs
             )
             context = {"client_session": self, "message": "Unclosed client session"}
             if self._source_traceback is not None:
@@ -377,7 +377,7 @@ async def _request(
         ssl: Optional[Union[SSLContext, bool, Fingerprint]] = None,
         proxy_headers: Optional[LooseHeaders] = None,
         trace_request_ctx: Optional[SimpleNamespace] = None,
-        read_bufsize: Optional[int] = None
+        read_bufsize: Optional[int] = None,
     ) -> ClientResponse:
 
         # NOTE: timeout clamps existing connect and read timeouts.  We cannot
@@ -529,7 +529,7 @@ async def _request(
                             )
                     except asyncio.TimeoutError as exc:
                         raise ServerTimeoutError(
-                            "Connection timeout " "to host {0}".format(url)
+                            "Connection timeout " "to host {}".format(url)
                         ) from exc
 
                     assert conn.transport is not None
@@ -677,7 +677,7 @@ def ws_connect(
         ssl_context: Optional[SSLContext] = None,
         proxy_headers: Optional[LooseHeaders] = None,
         compress: int = 0,
-        max_msg_size: int = 4 * 1024 * 1024
+        max_msg_size: int = 4 * 1024 * 1024,
     ) -> "_WSRequestContextManager":
         """Initiate websocket connection."""
         return _WSRequestContextManager(
@@ -727,7 +727,7 @@ async def _ws_connect(
         ssl_context: Optional[SSLContext] = None,
         proxy_headers: Optional[LooseHeaders] = None,
         compress: int = 0,
-        max_msg_size: int = 4 * 1024 * 1024
+        max_msg_size: int = 4 * 1024 * 1024,
     ) -> ClientWebSocketResponse:
 
         if headers is None:
@@ -1207,7 +1207,7 @@ def request(
     version: HttpVersion = http.HttpVersion11,
     connector: Optional[BaseConnector] = None,
     read_bufsize: Optional[int] = None,
-    loop: Optional[asyncio.AbstractEventLoop] = None
+    loop: Optional[asyncio.AbstractEventLoop] = None,
 ) -> _SessionRequestContextManager:
     """Constructs and sends a request. Returns response object.
     method - HTTP method
diff --git a/aiohttp/client_exceptions.py b/aiohttp/client_exceptions.py
index ef6bec926f8..eb135a24062 100644
--- a/aiohttp/client_exceptions.py
+++ b/aiohttp/client_exceptions.py
@@ -64,7 +64,7 @@ def __init__(
         code: Optional[int] = None,
         status: Optional[int] = None,
         message: str = "",
-        headers: Optional[LooseHeaders] = None
+        headers: Optional[LooseHeaders] = None,
     ) -> None:
         self.request_info = request_info
         if code is not None:
@@ -90,21 +90,21 @@ def __init__(
         self.args = (request_info, history)
 
     def __str__(self) -> str:
-        return "%s, message=%r, url=%r" % (
+        return "{}, message={!r}, url={!r}".format(
             self.status,
             self.message,
             self.request_info.real_url,
         )
 
     def __repr__(self) -> str:
-        args = "%r, %r" % (self.request_info, self.history)
+        args = f"{self.request_info!r}, {self.history!r}"
         if self.status != 0:
-            args += ", status=%r" % (self.status,)
+            args += f", status={self.status!r}"
         if self.message != "":
-            args += ", message=%r" % (self.message,)
+            args += f", message={self.message!r}"
         if self.headers is not None:
-            args += ", headers=%r" % (self.headers,)
-        return "%s(%s)" % (type(self).__name__, args)
+            args += f", headers={self.headers!r}"
+        return "{}({})".format(type(self).__name__, args)
 
     @property
     def code(self) -> int:
@@ -257,7 +257,7 @@ def url(self) -> Any:
         return self.args[0]
 
     def __repr__(self) -> str:
-        return "<{} {}>".format(self.__class__.__name__, self.url)
+        return f"<{self.__class__.__name__} {self.url}>"
 
 
 class ClientSSLError(ClientConnectorError):
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index 1c0f922cdb7..a324b53b861 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -267,7 +267,7 @@ def __init__(
         session: Optional["ClientSession"] = None,
         ssl: Union[SSLContext, bool, Fingerprint, None] = None,
         proxy_headers: Optional[LooseHeaders] = None,
-        traces: Optional[List["Trace"]] = None
+        traces: Optional[List["Trace"]] = None,
     ):
 
         if loop is None:
@@ -381,7 +381,7 @@ def update_version(self, version: Union[http.HttpVersion, str]) -> None:
                 version = http.HttpVersion(int(v[0]), int(v[1]))
             except ValueError:
                 raise ValueError(
-                    "Can not parse http version number: {}".format(version)
+                    f"Can not parse http version number: {version}"
                 ) from None
         self.version = version
 
@@ -392,7 +392,7 @@ def update_headers(self, headers: Optional[LooseHeaders]) -> None:
         # add host
         netloc = cast(str, self.url.raw_host)
         if helpers.is_ipv6_address(netloc):
-            netloc = "[{}]".format(netloc)
+            netloc = f"[{netloc}]"
         if self.url.port is not None and not self.url.is_default_port():
             netloc += ":" + str(self.url.port)
         self.headers[hdrs.HOST] = netloc
@@ -615,8 +615,8 @@ async def send(self, conn: "Connection") -> "ClientResponse":
             connect_host = self.url.raw_host
             assert connect_host is not None
             if helpers.is_ipv6_address(connect_host):
-                connect_host = "[{}]".format(connect_host)
-            path = "{}:{}".format(connect_host, self.url.port)
+                connect_host = f"[{connect_host}]"
+            path = f"{connect_host}:{self.url.port}"
         elif self.proxy and not self.is_ssl():
             path = str(self.url)
         else:
@@ -731,7 +731,7 @@ def __init__(
         request_info: RequestInfo,
         traces: List["Trace"],
         loop: asyncio.AbstractEventLoop,
-        session: "ClientSession"
+        session: "ClientSession",
     ) -> None:
         assert isinstance(url, URL)
 
@@ -808,9 +808,7 @@ def __del__(self, _warnings: Any = warnings) -> None:
                     kwargs = {"source": self}
                 else:
                     kwargs = {}
-                _warnings.warn(
-                    "Unclosed response {!r}".format(self), ResourceWarning, **kwargs
-                )
+                _warnings.warn(f"Unclosed response {self!r}", ResourceWarning, **kwargs)
                 context = {"client_response": self, "message": "Unclosed response"}
                 if self._source_traceback:
                     context["source_traceback"] = self._source_traceback
@@ -1087,7 +1085,7 @@ async def json(
         *,
         encoding: Optional[str] = None,
         loads: JSONDecoder = DEFAULT_JSON_DECODER,
-        content_type: Optional[str] = "application/json"
+        content_type: Optional[str] = "application/json",
     ) -> Any:
         """Read and decodes JSON response."""
         if self._body is None:
diff --git a/aiohttp/client_ws.py b/aiohttp/client_ws.py
index 1a5b6c06800..a90c60d9d3c 100644
--- a/aiohttp/client_ws.py
+++ b/aiohttp/client_ws.py
@@ -40,7 +40,7 @@ def __init__(
         receive_timeout: Optional[float] = None,
         heartbeat: Optional[float] = None,
         compress: int = 0,
-        client_notakeover: bool = False
+        client_notakeover: bool = False,
     ) -> None:
         self._response = response
         self._conn = response.connection
@@ -159,7 +159,7 @@ async def send_json(
         data: Any,
         compress: Optional[int] = None,
         *,
-        dumps: JSONEncoder = DEFAULT_JSON_ENCODER
+        dumps: JSONEncoder = DEFAULT_JSON_ENCODER,
     ) -> None:
         await self.send_str(dumps(data), compress=compress)
 
@@ -273,24 +273,20 @@ async def receive(self, timeout: Optional[float] = None) -> WSMessage:
     async def receive_str(self, *, timeout: Optional[float] = None) -> str:
         msg = await self.receive(timeout)
         if msg.type != WSMsgType.TEXT:
-            raise TypeError(
-                "Received message {}:{!r} is not str".format(msg.type, msg.data)
-            )
+            raise TypeError(f"Received message {msg.type}:{msg.data!r} is not str")
         return msg.data
 
     async def receive_bytes(self, *, timeout: Optional[float] = None) -> bytes:
         msg = await self.receive(timeout)
         if msg.type != WSMsgType.BINARY:
-            raise TypeError(
-                "Received message {}:{!r} is not bytes".format(msg.type, msg.data)
-            )
+            raise TypeError(f"Received message {msg.type}:{msg.data!r} is not bytes")
         return msg.data
 
     async def receive_json(
         self,
         *,
         loads: JSONDecoder = DEFAULT_JSON_DECODER,
-        timeout: Optional[float] = None
+        timeout: Optional[float] = None,
     ) -> Any:
         data = await self.receive_str(timeout=timeout)
         return loads(data)
diff --git a/aiohttp/connector.py b/aiohttp/connector.py
index e2fed54da09..d05687c2493 100644
--- a/aiohttp/connector.py
+++ b/aiohttp/connector.py
@@ -109,7 +109,7 @@ def __init__(
             self._source_traceback = traceback.extract_stack(sys._getframe(1))
 
     def __repr__(self) -> str:
-        return "Connection<{}>".format(self._key)
+        return f"Connection<{self._key}>"
 
     def __del__(self, _warnings: Any = warnings) -> None:
         if self._protocol is not None:
@@ -117,9 +117,7 @@ def __del__(self, _warnings: Any = warnings) -> None:
                 kwargs = {"source": self}
             else:
                 kwargs = {}
-            _warnings.warn(
-                "Unclosed connection {!r}".format(self), ResourceWarning, **kwargs
-            )
+            _warnings.warn(f"Unclosed connection {self!r}", ResourceWarning, **kwargs)
             if self._loop.is_closed():
                 return
 
@@ -213,7 +211,7 @@ def __init__(
         limit: int = 100,
         limit_per_host: int = 0,
         enable_cleanup_closed: bool = False,
-        loop: Optional[asyncio.AbstractEventLoop] = None
+        loop: Optional[asyncio.AbstractEventLoop] = None,
     ) -> None:
 
         if force_close:
@@ -276,9 +274,7 @@ def __del__(self, _warnings: Any = warnings) -> None:
             kwargs = {"source": self}
         else:
             kwargs = {}
-        _warnings.warn(
-            "Unclosed connector {!r}".format(self), ResourceWarning, **kwargs
-        )
+        _warnings.warn(f"Unclosed connector {self!r}", ResourceWarning, **kwargs)
         context = {
             "connector": self,
             "connections": conns,
@@ -640,7 +636,7 @@ def _release(
         key: "ConnectionKey",
         protocol: ResponseHandler,
         *,
-        should_close: bool = False
+        should_close: bool = False,
     ) -> None:
         if self._closed:
             # acquired connection is already released on connector closing
@@ -757,7 +753,7 @@ def __init__(
         limit: int = 100,
         limit_per_host: int = 0,
         enable_cleanup_closed: bool = False,
-        loop: Optional[asyncio.AbstractEventLoop] = None
+        loop: Optional[asyncio.AbstractEventLoop] = None,
     ):
         super().__init__(
             keepalive_timeout=keepalive_timeout,
@@ -968,7 +964,7 @@ async def _wrap_create_connection(
         req: "ClientRequest",
         timeout: "ClientTimeout",
         client_error: Type[Exception] = ClientConnectorError,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> Tuple[asyncio.Transport, ResponseHandler]:
         try:
             with CeilTimeout(timeout.sock_connect):
@@ -986,7 +982,7 @@ async def _create_direct_connection(
         traces: List["Trace"],
         timeout: "ClientTimeout",
         *,
-        client_error: Type[Exception] = ClientConnectorError
+        client_error: Type[Exception] = ClientConnectorError,
     ) -> Tuple[asyncio.Transport, ResponseHandler]:
         sslcontext = self._get_ssl_context(req)
         fingerprint = self._get_fingerprint(req)
diff --git a/aiohttp/frozenlist.py b/aiohttp/frozenlist.py
index 42ddcd5ab46..46b26108cfa 100644
--- a/aiohttp/frozenlist.py
+++ b/aiohttp/frozenlist.py
@@ -58,7 +58,7 @@ def insert(self, pos, item):
         self._items.insert(pos, item)
 
     def __repr__(self):
-        return "<FrozenList(frozen={}, {!r})>".format(self._frozen, self._items)
+        return f"<FrozenList(frozen={self._frozen}, {self._items!r})>"
 
 
 PyFrozenList = FrozenList
diff --git a/aiohttp/helpers.py b/aiohttp/helpers.py
index 23cd6af4cde..e67cbd11068 100644
--- a/aiohttp/helpers.py
+++ b/aiohttp/helpers.py
@@ -94,8 +94,8 @@ def all_tasks(
 )  # type: bool
 
 
-CHAR = set(chr(i) for i in range(0, 128))
-CTL = set(chr(i) for i in range(0, 32)) | {
+CHAR = {chr(i) for i in range(0, 128)}
+CTL = {chr(i) for i in range(0, 32)} | {
     chr(127),
 }
 SEPARATORS = {
@@ -184,7 +184,7 @@ def from_url(cls, url: URL, *, encoding: str = "latin1") -> Optional["BasicAuth"
 
     def encode(self) -> str:
         """Encode credentials."""
-        creds = ("%s:%s" % (self.login, self.password)).encode(self.encoding)
+        creds = (f"{self.login}:{self.password}").encode(self.encoding)
         return "Basic %s" % base64.b64encode(creds).decode(self.encoding)
 
 
@@ -777,4 +777,4 @@ def __bool__(self) -> bool:
 
     def __repr__(self) -> str:
         content = ", ".join(map(repr, self._maps))
-        return "ChainMapProxy({})".format(content)
+        return f"ChainMapProxy({content})"
diff --git a/aiohttp/http_exceptions.py b/aiohttp/http_exceptions.py
index 0c1246a6b8f..c885f80f322 100644
--- a/aiohttp/http_exceptions.py
+++ b/aiohttp/http_exceptions.py
@@ -35,10 +35,10 @@ def __init__(
         self.message = message
 
     def __str__(self) -> str:
-        return "%s, message=%r" % (self.code, self.message)
+        return f"{self.code}, message={self.message!r}"
 
     def __repr__(self) -> str:
-        return "<%s: %s>" % (self.__class__.__name__, self)
+        return f"<{self.__class__.__name__}: {self}>"
 
 
 class BadHttpMessage(HttpProcessingError):
@@ -78,7 +78,7 @@ def __init__(
         self, line: str, limit: str = "Unknown", actual_size: str = "Unknown"
     ) -> None:
         super().__init__(
-            "Got more than %s bytes (%s) when reading %s." % (limit, actual_size, line)
+            f"Got more than {limit} bytes ({actual_size}) when reading {line}."
         )
         self.args = (line, limit, actual_size)
 
@@ -87,7 +87,7 @@ class InvalidHeader(BadHttpMessage):
     def __init__(self, hdr: Union[bytes, str]) -> None:
         if isinstance(hdr, bytes):
             hdr = hdr.decode("utf-8", "surrogateescape")
-        super().__init__("Invalid HTTP Header: {}".format(hdr))
+        super().__init__(f"Invalid HTTP Header: {hdr}")
         self.hdr = hdr
         self.args = (hdr,)
 
diff --git a/aiohttp/http_websocket.py b/aiohttp/http_websocket.py
index 965656e0eed..5cdaeea43c0 100644
--- a/aiohttp/http_websocket.py
+++ b/aiohttp/http_websocket.py
@@ -298,7 +298,7 @@ def _feed_data(self, data: bytes) -> Tuple[bool, bytes]:
                     if close_code < 3000 and close_code not in ALLOWED_CLOSE_CODES:
                         raise WebSocketError(
                             WSCloseCode.PROTOCOL_ERROR,
-                            "Invalid close code: {}".format(close_code),
+                            f"Invalid close code: {close_code}",
                         )
                     try:
                         close_message = payload[2:].decode("utf-8")
@@ -310,7 +310,7 @@ def _feed_data(self, data: bytes) -> Tuple[bool, bytes]:
                 elif payload:
                     raise WebSocketError(
                         WSCloseCode.PROTOCOL_ERROR,
-                        "Invalid close frame: {} {} {!r}".format(fin, opcode, payload),
+                        f"Invalid close frame: {fin} {opcode} {payload!r}",
                     )
                 else:
                     msg = WSMessage(WSMsgType.CLOSE, 0, "")
@@ -332,7 +332,7 @@ def _feed_data(self, data: bytes) -> Tuple[bool, bytes]:
                 and self._opcode is None
             ):
                 raise WebSocketError(
-                    WSCloseCode.PROTOCOL_ERROR, "Unexpected opcode={!r}".format(opcode)
+                    WSCloseCode.PROTOCOL_ERROR, f"Unexpected opcode={opcode!r}"
                 )
             else:
                 # load text/binary
@@ -577,7 +577,7 @@ def __init__(
         limit: int = DEFAULT_LIMIT,
         random: Any = random.Random(),
         compress: int = 0,
-        notakeover: bool = False
+        notakeover: bool = False,
     ) -> None:
         self.protocol = protocol
         self.transport = transport
diff --git a/aiohttp/multipart.py b/aiohttp/multipart.py
index 8b406dfdf21..d3a366440dc 100644
--- a/aiohttp/multipart.py
+++ b/aiohttp/multipart.py
@@ -90,7 +90,7 @@ def is_continuous_param(string: str) -> bool:
         return substring.isdigit()
 
     def unescape(text: str, *, chars: str = "".join(map(re.escape, CHAR))) -> str:
-        return re.sub("\\\\([{}])".format(chars), "\\1", text)
+        return re.sub(f"\\\\([{chars}])", "\\1", text)
 
     if not header:
         return None, {}
@@ -151,7 +151,7 @@ def unescape(text: str, *, chars: str = "".join(map(re.escape, CHAR))) -> str:
             elif parts:
                 # maybe just ; in filename, in any case this is just
                 # one case fix, for proper fix we need to redesign parser
-                _value = "%s;%s" % (value, parts[0])
+                _value = "{};{}".format(value, parts[0])
                 if is_quoted(_value):
                     parts.pop(0)
                     value = unescape(_value[1:-1].lstrip("\\/"))
@@ -291,7 +291,7 @@ async def read(self, *, decode: bool = False) -> bytes:
             return b""
         data = bytearray()
         while not self._at_eof:
-            data.extend((await self.read_chunk(self.chunk_size)))
+            data.extend(await self.read_chunk(self.chunk_size))
         if decode:
             return self.decode(data)
         return data
@@ -453,7 +453,7 @@ def _decode_content(self, data: bytes) -> bytes:
         elif encoding == "identity":
             return data
         else:
-            raise RuntimeError("unknown content encoding: {}".format(encoding))
+            raise RuntimeError(f"unknown content encoding: {encoding}")
 
     def _decode_content_transfer(self, data: bytes) -> bytes:
         encoding = self.headers.get(CONTENT_TRANSFER_ENCODING, "").lower()
@@ -678,9 +678,7 @@ async def _read_boundary(self) -> None:
             else:
                 self._unread.extend([next_line, epilogue])
         else:
-            raise ValueError(
-                "Invalid boundary %r, expected %r" % (chunk, self._boundary)
-            )
+            raise ValueError(f"Invalid boundary {chunk!r}, expected {self._boundary!r}")
 
     async def _read_headers(self) -> "CIMultiDictProxy[str]":
         lines = [b""]
@@ -720,7 +718,7 @@ def __init__(self, subtype: str = "mixed", boundary: Optional[str] = None) -> No
             self._boundary = boundary.encode("ascii")
         except UnicodeEncodeError:
             raise ValueError("boundary should contain ASCII only chars") from None
-        ctype = "multipart/{}; boundary={}".format(subtype, self._boundary_value)
+        ctype = f"multipart/{subtype}; boundary={self._boundary_value}"
 
         super().__init__(None, content_type=ctype)
 
@@ -808,7 +806,7 @@ def append_payload(self, payload: Payload) -> Payload:
             "",
         ).lower()  # type: Optional[str]
         if encoding and encoding not in ("deflate", "gzip", "identity"):
-            raise RuntimeError("unknown content encoding: {}".format(encoding))
+            raise RuntimeError(f"unknown content encoding: {encoding}")
         if encoding == "identity":
             encoding = None
 
diff --git a/aiohttp/payload.py b/aiohttp/payload.py
index 78389c7679d..10afed65806 100644
--- a/aiohttp/payload.py
+++ b/aiohttp/payload.py
@@ -121,7 +121,7 @@ def register(
         elif order is Order.try_last:
             self._last.append((factory, type))
         else:
-            raise ValueError("Unsupported order {!r}".format(order))
+            raise ValueError(f"Unsupported order {order!r}")
 
 
 class Payload(ABC):
@@ -138,7 +138,7 @@ def __init__(
         content_type: Optional[str] = sentinel,
         filename: Optional[str] = None,
         encoding: Optional[str] = None,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> None:
         self._encoding = encoding
         self._filename = filename
@@ -246,7 +246,7 @@ def __init__(
         *args: Any,
         encoding: Optional[str] = None,
         content_type: Optional[str] = None,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> None:
 
         if encoding is None:
@@ -306,7 +306,7 @@ def __init__(
         *args: Any,
         encoding: Optional[str] = None,
         content_type: Optional[str] = None,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> None:
 
         if encoding is None:
@@ -374,7 +374,7 @@ def __init__(
         content_type: str = "application/json",
         dumps: JSONEncoder = json.dumps,
         *args: Any,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> None:
 
         super().__init__(
diff --git a/aiohttp/test_utils.py b/aiohttp/test_utils.py
index f415934503f..0a414565a11 100644
--- a/aiohttp/test_utils.py
+++ b/aiohttp/test_utils.py
@@ -94,7 +94,7 @@ def __init__(
         host: str = "127.0.0.1",
         port: Optional[int] = None,
         skip_url_asserts: bool = False,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> None:
         self._loop = loop
         self.runner = None  # type: Optional[BaseRunner]
@@ -131,7 +131,7 @@ async def start_server(
             else:
                 scheme = "http"
             self.scheme = scheme
-        self._root = URL("{}://{}:{}".format(self.scheme, self.host, self.port))
+        self._root = URL(f"{self.scheme}://{self.host}:{self.port}")
 
     @abstractmethod  # pragma: no cover
     async def _make_runner(self, **kwargs: Any) -> BaseRunner:
@@ -215,7 +215,7 @@ def __init__(
         scheme: Union[str, object] = sentinel,
         host: str = "127.0.0.1",
         port: Optional[int] = None,
-        **kwargs: Any
+        **kwargs: Any,
     ):
         self.app = app
         super().__init__(scheme=scheme, host=host, port=port, **kwargs)
@@ -232,7 +232,7 @@ def __init__(
         scheme: Union[str, object] = sentinel,
         host: str = "127.0.0.1",
         port: Optional[int] = None,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> None:
         self._handler = handler
         super().__init__(scheme=scheme, host=host, port=port, **kwargs)
@@ -258,7 +258,7 @@ def __init__(
         *,
         cookie_jar: Optional[AbstractCookieJar] = None,
         loop: Optional[asyncio.AbstractEventLoop] = None,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> None:
         if not isinstance(server, BaseTestServer):
             raise TypeError(
@@ -593,7 +593,7 @@ def make_mocked_request(
     payload: Any = sentinel,
     sslcontext: Optional[SSLContext] = None,
     client_max_size: int = 1024 ** 2,
-    loop: Any = ...
+    loop: Any = ...,
 ) -> Any:
     """Creates mocked web.Request testing purposes.
 
diff --git a/aiohttp/web.py b/aiohttp/web.py
index 00e6eb706df..557e3c3b4d0 100644
--- a/aiohttp/web.py
+++ b/aiohttp/web.py
@@ -300,7 +300,7 @@ async def _run_app(
     access_log: Optional[logging.Logger] = access_logger,
     handle_signals: bool = True,
     reuse_address: Optional[bool] = None,
-    reuse_port: Optional[bool] = None
+    reuse_port: Optional[bool] = None,
 ) -> None:
     # A internal functio to actually do all dirty job for application running
     if asyncio.iscoroutine(app):
@@ -473,7 +473,7 @@ def run_app(
     access_log: Optional[logging.Logger] = access_logger,
     handle_signals: bool = True,
     reuse_address: Optional[bool] = None,
-    reuse_port: Optional[bool] = None
+    reuse_port: Optional[bool] = None,
 ) -> None:
     """Run an app locally"""
     loop = asyncio.get_event_loop()
@@ -558,11 +558,11 @@ def main(argv: List[str]) -> None:
     try:
         module = import_module(mod_str)
     except ImportError as ex:
-        arg_parser.error("unable to import %s: %s" % (mod_str, ex))
+        arg_parser.error(f"unable to import {mod_str}: {ex}")
     try:
         func = getattr(module, func_str)
     except AttributeError:
-        arg_parser.error("module %r has no attribute %r" % (mod_str, func_str))
+        arg_parser.error(f"module {mod_str!r} has no attribute {func_str!r}")
 
     # Compatibility logic
     if args.path is not None and not hasattr(socket, "AF_UNIX"):
diff --git a/aiohttp/web_app.py b/aiohttp/web_app.py
index fb35b49a873..1f0e41a7e11 100644
--- a/aiohttp/web_app.py
+++ b/aiohttp/web_app.py
@@ -110,7 +110,7 @@ def __init__(
         handler_args: Optional[Mapping[str, Any]] = None,
         client_max_size: int = 1024 ** 2,
         loop: Optional[asyncio.AbstractEventLoop] = None,
-        debug: Any = ...  # mypy doesn't support ellipsis
+        debug: Any = ...,  # mypy doesn't support ellipsis
     ) -> None:
         if router is None:
             router = UrlDispatcher()
@@ -365,7 +365,7 @@ def _make_handler(
         *,
         loop: Optional[asyncio.AbstractEventLoop] = None,
         access_log_class: Type[AbstractAccessLogger] = AccessLogger,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> Server:
 
         if not issubclass(access_log_class, AbstractAccessLogger):
@@ -387,7 +387,7 @@ def _make_handler(
             self._handle,  # type: ignore
             request_factory=self._make_request,
             loop=self._loop,
-            **kwargs
+            **kwargs,
         )
 
     def make_handler(
@@ -395,7 +395,7 @@ def make_handler(
         *,
         loop: Optional[asyncio.AbstractEventLoop] = None,
         access_log_class: Type[AbstractAccessLogger] = AccessLogger,
-        **kwargs: Any
+        **kwargs: Any,
     ) -> Server:
 
         warnings.warn(
@@ -544,7 +544,7 @@ async def _on_cleanup(self, app: Application) -> None:
             except Exception as exc:
                 errors.append(exc)
             else:
-                errors.append(RuntimeError("{!r} has more than one 'yield'".format(it)))
+                errors.append(RuntimeError(f"{it!r} has more than one 'yield'"))
         if errors:
             if len(errors) == 1:
                 raise errors[0]
diff --git a/aiohttp/web_exceptions.py b/aiohttp/web_exceptions.py
index 30fabadfb18..2eadca0386a 100644
--- a/aiohttp/web_exceptions.py
+++ b/aiohttp/web_exceptions.py
@@ -89,7 +89,7 @@ def __init__(
         reason: Optional[str] = None,
         body: Any = None,
         text: Optional[str] = None,
-        content_type: Optional[str] = None
+        content_type: Optional[str] = None,
     ) -> None:
         if body is not None:
             warnings.warn(
@@ -107,7 +107,7 @@ def __init__(
         )
         Exception.__init__(self, self.reason)
         if self.body is None and not self.empty_body:
-            self.text = "{}: {}".format(self.status, self.reason)
+            self.text = f"{self.status}: {self.reason}"
 
     def __bool__(self) -> bool:
         return True
@@ -169,7 +169,7 @@ def __init__(
         reason: Optional[str] = None,
         body: Any = None,
         text: Optional[str] = None,
-        content_type: Optional[str] = None
+        content_type: Optional[str] = None,
     ) -> None:
         if not location:
             raise ValueError("HTTP redirects need a location to redirect to.")
@@ -262,7 +262,7 @@ def __init__(
         reason: Optional[str] = None,
         body: Any = None,
         text: Optional[str] = None,
-        content_type: Optional[str] = None
+        content_type: Optional[str] = None,
     ) -> None:
         allow = ",".join(sorted(allowed_methods))
         super().__init__(
@@ -372,7 +372,7 @@ def __init__(
         reason: Optional[str] = None,
         body: Any = None,
         text: Optional[str] = None,
-        content_type: Optional[str] = None
+        content_type: Optional[str] = None,
     ) -> None:
         super().__init__(
             headers=headers,
diff --git a/aiohttp/web_fileresponse.py b/aiohttp/web_fileresponse.py
index 4f74b816014..2b497085a2e 100644
--- a/aiohttp/web_fileresponse.py
+++ b/aiohttp/web_fileresponse.py
@@ -282,7 +282,7 @@ async def prepare(self, request: "BaseRequest") -> Optional[AbstractStreamWriter
                 #
                 # Will do the same below. Many servers ignore this and do not
                 # send a Content-Range header with HTTP 416
-                self.headers[hdrs.CONTENT_RANGE] = "bytes */{0}".format(file_size)
+                self.headers[hdrs.CONTENT_RANGE] = f"bytes */{file_size}"
                 self.set_status(HTTPRequestRangeNotSatisfiable.status_code)
                 return await super().prepare(request)
 
@@ -318,7 +318,7 @@ async def prepare(self, request: "BaseRequest") -> Optional[AbstractStreamWriter
                     # suffix-byte-range-spec with a non-zero suffix-length,
                     # then the byte-range-set is satisfiable. Otherwise, the
                     # byte-range-set is unsatisfiable.
-                    self.headers[hdrs.CONTENT_RANGE] = "bytes */{0}".format(file_size)
+                    self.headers[hdrs.CONTENT_RANGE] = f"bytes */{file_size}"
                     self.set_status(HTTPRequestRangeNotSatisfiable.status_code)
                     return await super().prepare(request)
 
@@ -341,7 +341,7 @@ async def prepare(self, request: "BaseRequest") -> Optional[AbstractStreamWriter
         real_start = cast(int, start)
 
         if status == HTTPPartialContent.status_code:
-            self.headers[hdrs.CONTENT_RANGE] = "bytes {0}-{1}/{2}".format(
+            self.headers[hdrs.CONTENT_RANGE] = "bytes {}-{}/{}".format(
                 real_start, real_start + count - 1, file_size
             )
 
diff --git a/aiohttp/web_log.py b/aiohttp/web_log.py
index b2e83a6f326..4cfa57929a9 100644
--- a/aiohttp/web_log.py
+++ b/aiohttp/web_log.py
@@ -154,7 +154,7 @@ def _format_P(request: BaseRequest, response: StreamResponse, time: float) -> st
     def _format_r(request: BaseRequest, response: StreamResponse, time: float) -> str:
         if request is None:
             return "-"
-        return "%s %s HTTP/%s.%s" % (
+        return "{} {} HTTP/{}.{}".format(
             request.method,
             request.path_qs,
             request.version.major,
diff --git a/aiohttp/web_protocol.py b/aiohttp/web_protocol.py
index bc51de41b8e..9b18f4aa955 100644
--- a/aiohttp/web_protocol.py
+++ b/aiohttp/web_protocol.py
@@ -149,7 +149,7 @@ def __init__(
         max_headers: int = 32768,
         max_field_size: int = 8190,
         lingering_time: float = 10.0,
-        read_bufsize: int = 2 ** 16
+        read_bufsize: int = 2 ** 16,
     ):
 
         super().__init__(loop)
@@ -622,7 +622,7 @@ def handle_error(
             if "text/html" in request.headers.get("Accept", ""):
                 if tb:
                     tb = html_escape(tb)
-                    msg = "<h2>Traceback:</h2>\n<pre>{}</pre>".format(tb)
+                    msg = f"<h2>Traceback:</h2>\n<pre>{tb}</pre>"
                 message = (
                     "<html><head>"
                     "<title>{title}</title>"
diff --git a/aiohttp/web_request.py b/aiohttp/web_request.py
index 8dd21dc2c79..808f8877c5b 100644
--- a/aiohttp/web_request.py
+++ b/aiohttp/web_request.py
@@ -66,7 +66,7 @@ class FileField:
 _TCHAR = string.digits + string.ascii_letters + r"!#$%&'*+.^_`|~-"
 # '-' at the end to prevent interpretation as range in a char class
 
-_TOKEN = r"[{tchar}]+".format(tchar=_TCHAR)
+_TOKEN = fr"[{_TCHAR}]+"
 
 _QDTEXT = r"[{}]".format(
     r"".join(chr(c) for c in (0x09, 0x20, 0x21) + tuple(range(0x23, 0x7F)))
@@ -139,7 +139,7 @@ def __init__(
         state: Optional[Dict[str, Any]] = None,
         scheme: Optional[str] = None,
         host: Optional[str] = None,
-        remote: Optional[str] = None
+        remote: Optional[str] = None,
     ) -> None:
         if state is None:
             state = {}
@@ -183,7 +183,7 @@ def clone(
         headers: LooseHeaders = sentinel,
         scheme: str = sentinel,
         host: str = sentinel,
-        remote: str = sentinel
+        remote: str = sentinel,
     ) -> "BaseRequest":
         """Clone itself with replacement some attributes.
 
@@ -229,7 +229,7 @@ def clone(
             self._loop,
             client_max_size=self._client_max_size,
             state=self._state.copy(),
-            **kwargs
+            **kwargs,
         )
 
     @property
@@ -778,7 +778,7 @@ def clone(
         headers: LooseHeaders = sentinel,
         scheme: str = sentinel,
         host: str = sentinel,
-        remote: str = sentinel
+        remote: str = sentinel,
     ) -> "Request":
         ret = super().clone(
             method=method,
diff --git a/aiohttp/web_response.py b/aiohttp/web_response.py
index 50a0dbe9d6f..a3fa9f3c12a 100644
--- a/aiohttp/web_response.py
+++ b/aiohttp/web_response.py
@@ -73,7 +73,7 @@ def __init__(
         *,
         status: int = 200,
         reason: Optional[str] = None,
-        headers: Optional[LooseHeaders] = None
+        headers: Optional[LooseHeaders] = None,
     ) -> None:
         self._body = None
         self._keep_alive = None  # type: Optional[bool]
@@ -202,7 +202,7 @@ def set_cookie(
         secure: Optional[bool] = None,
         httponly: Optional[bool] = None,
         version: Optional[str] = None,
-        samesite: Optional[str] = None
+        samesite: Optional[str] = None,
     ) -> None:
         """Set or update response cookie.
 
@@ -343,7 +343,7 @@ def _generate_content_type_header(
     ) -> None:
         assert self._content_dict is not None
         assert self._content_type is not None
-        params = "; ".join("{}={}".format(k, v) for k, v in self._content_dict.items())
+        params = "; ".join(f"{k}={v}" for k, v in self._content_dict.items())
         if params:
             ctype = self._content_type + "; " + params
         else:
@@ -500,10 +500,10 @@ def __repr__(self) -> str:
             info = "eof"
         elif self.prepared:
             assert self._req is not None
-            info = "{} {} ".format(self._req.method, self._req.path)
+            info = f"{self._req.method} {self._req.path} "
         else:
             info = "not prepared"
-        return "<{} {} {}>".format(self.__class__.__name__, self.reason, info)
+        return f"<{self.__class__.__name__} {self.reason} {info}>"
 
     def __getitem__(self, key: str) -> Any:
         return self._state[key]
@@ -539,7 +539,7 @@ def __init__(
         content_type: Optional[str] = None,
         charset: Optional[str] = None,
         zlib_executor_size: Optional[int] = None,
-        zlib_executor: Optional[Executor] = None
+        zlib_executor: Optional[Executor] = None,
     ) -> None:
         if body is not None and text is not None:
             raise ValueError("body and text are not allowed together")
@@ -694,7 +694,7 @@ async def write_eof(self, data: bytes = b"") -> None:
             body = self._body  # type: Optional[Union[bytes, Payload]]
         else:
             body = self._compressed_body
-        assert not data, "data arg is not supported, got {!r}".format(data)
+        assert not data, f"data arg is not supported, got {data!r}"
         assert self._req is not None
         assert self._payload_writer is not None
         if body is not None:
@@ -764,7 +764,7 @@ def json_response(
     reason: Optional[str] = None,
     headers: Optional[LooseHeaders] = None,
     content_type: str = "application/json",
-    dumps: JSONEncoder = json.dumps
+    dumps: JSONEncoder = json.dumps,
 ) -> Response:
     if data is not sentinel:
         if text or body:
diff --git a/aiohttp/web_routedef.py b/aiohttp/web_routedef.py
index 7541f3e1d54..16c3b0d3522 100644
--- a/aiohttp/web_routedef.py
+++ b/aiohttp/web_routedef.py
@@ -67,7 +67,7 @@ class RouteDef(AbstractRouteDef):
     def __repr__(self) -> str:
         info = []
         for name, value in sorted(self.kwargs.items()):
-            info.append(", {}={!r}".format(name, value))
+            info.append(f", {name}={value!r}")
         return "<RouteDef {method} {path} -> {handler.__name__!r}" "{info}>".format(
             method=self.method, path=self.path, handler=self.handler, info="".join(info)
         )
@@ -91,7 +91,7 @@ class StaticDef(AbstractRouteDef):
     def __repr__(self) -> str:
         info = []
         for name, value in sorted(self.kwargs.items()):
-            info.append(", {}={!r}".format(name, value))
+            info.append(f", {name}={value!r}")
         return "<StaticDef {prefix} -> {path}" "{info}>".format(
             prefix=self.prefix, path=self.path, info="".join(info)
         )
@@ -120,7 +120,7 @@ def get(
     *,
     name: Optional[str] = None,
     allow_head: bool = True,
-    **kwargs: Any
+    **kwargs: Any,
 ) -> RouteDef:
     return route(
         hdrs.METH_GET, path, handler, name=name, allow_head=allow_head, **kwargs
diff --git a/aiohttp/web_runner.py b/aiohttp/web_runner.py
index 214c53fda1e..25ac28a7a89 100644
--- a/aiohttp/web_runner.py
+++ b/aiohttp/web_runner.py
@@ -45,7 +45,7 @@ def __init__(
         *,
         shutdown_timeout: float = 60.0,
         ssl_context: Optional[SSLContext] = None,
-        backlog: int = 128
+        backlog: int = 128,
     ) -> None:
         if runner.server is None:
             raise RuntimeError("Call runner.setup() before making a site")
@@ -92,7 +92,7 @@ def __init__(
         ssl_context: Optional[SSLContext] = None,
         backlog: int = 128,
         reuse_address: Optional[bool] = None,
-        reuse_port: Optional[bool] = None
+        reuse_port: Optional[bool] = None,
     ) -> None:
         super().__init__(
             runner,
@@ -139,7 +139,7 @@ def __init__(
         *,
         shutdown_timeout: float = 60.0,
         ssl_context: Optional[SSLContext] = None,
-        backlog: int = 128
+        backlog: int = 128,
     ) -> None:
         super().__init__(
             runner,
@@ -152,7 +152,7 @@ def __init__(
     @property
     def name(self) -> str:
         scheme = "https" if self._ssl_context else "http"
-        return "{}://unix:{}:".format(scheme, self._path)
+        return f"{scheme}://unix:{self._path}:"
 
     async def start(self) -> None:
         await super().start()
@@ -201,7 +201,7 @@ def __init__(
         *,
         shutdown_timeout: float = 60.0,
         ssl_context: Optional[SSLContext] = None,
-        backlog: int = 128
+        backlog: int = 128,
     ) -> None:
         super().__init__(
             runner,
@@ -212,7 +212,7 @@ def __init__(
         self._sock = sock
         scheme = "https" if self._ssl_context else "http"
         if hasattr(socket, "AF_UNIX") and sock.family == socket.AF_UNIX:
-            name = "{}://unix:{}:".format(scheme, sock.getsockname())
+            name = f"{scheme}://unix:{sock.getsockname()}:"
         else:
             host, port = sock.getsockname()[:2]
             name = str(URL.build(scheme=scheme, host=host, port=port))
@@ -311,22 +311,16 @@ async def _cleanup_server(self) -> None:
 
     def _reg_site(self, site: BaseSite) -> None:
         if site in self._sites:
-            raise RuntimeError(
-                "Site {} is already registered in runner {}".format(site, self)
-            )
+            raise RuntimeError(f"Site {site} is already registered in runner {self}")
         self._sites.append(site)
 
     def _check_site(self, site: BaseSite) -> None:
         if site not in self._sites:
-            raise RuntimeError(
-                "Site {} is not registered in runner {}".format(site, self)
-            )
+            raise RuntimeError(f"Site {site} is not registered in runner {self}")
 
     def _unreg_site(self, site: BaseSite) -> None:
         if site not in self._sites:
-            raise RuntimeError(
-                "Site {} is not registered in runner {}".format(site, self)
-            )
+            raise RuntimeError(f"Site {site} is not registered in runner {self}")
         self._sites.remove(site)
 
 
diff --git a/aiohttp/web_urldispatcher.py b/aiohttp/web_urldispatcher.py
index 760afb698d0..4b6b99e4f1c 100644
--- a/aiohttp/web_urldispatcher.py
+++ b/aiohttp/web_urldispatcher.py
@@ -167,11 +167,11 @@ def __init__(
 
         assert asyncio.iscoroutinefunction(
             expect_handler
-        ), "Coroutine is expected, got {!r}".format(expect_handler)
+        ), f"Coroutine is expected, got {expect_handler!r}"
 
         method = method.upper()
         if not HTTP_METHOD_RE.match(method):
-            raise ValueError("{} is not allowed HTTP method".format(method))
+            raise ValueError(f"{method} is not allowed HTTP method")
 
         assert callable(handler), handler
         if asyncio.iscoroutinefunction(handler):
@@ -296,7 +296,7 @@ def freeze(self) -> None:
         self._frozen = True
 
     def __repr__(self) -> str:
-        return "<MatchInfo {}: {}>".format(super().__repr__(), self._route)
+        return f"<MatchInfo {super().__repr__()}: {self._route}>"
 
 
 class MatchInfoError(UrlMappingMatchInfo):
@@ -356,7 +356,7 @@ def add_route(
     def register_route(self, route: "ResourceRoute") -> None:
         assert isinstance(
             route, ResourceRoute
-        ), "Instance of Route class is required, got {!r}".format(route)
+        ), f"Instance of Route class is required, got {route!r}"
         self._routes.append(route)
 
     async def resolve(self, request: Request) -> _Resolve:
@@ -426,7 +426,7 @@ def url_for(self) -> URL:  # type: ignore
 
     def __repr__(self) -> str:
         name = "'" + self.name + "' " if self.name is not None else ""
-        return "<PlainResource {name} {path}>".format(name=name, path=self._path)
+        return f"<PlainResource {name} {self._path}>"
 
 
 class DynamicResource(Resource):
@@ -453,7 +453,7 @@ def __init__(self, path: str, *, name: Optional[str] = None) -> None:
                 continue
 
             if "{" in part or "}" in part:
-                raise ValueError("Invalid path '{}'['{}']".format(path, part))
+                raise ValueError(f"Invalid path '{path}'['{part}']")
 
             part = _requote_path(part)
             formatter += part
@@ -462,7 +462,7 @@ def __init__(self, path: str, *, name: Optional[str] = None) -> None:
         try:
             compiled = re.compile(pattern)
         except re.error as exc:
-            raise ValueError("Bad pattern '{}': {}".format(pattern, exc)) from None
+            raise ValueError(f"Bad pattern '{pattern}': {exc}") from None
         assert compiled.pattern.startswith(PATH_SEP)
         assert formatter.startswith("/")
         self._pattern = compiled
@@ -552,7 +552,7 @@ def __init__(
             if not directory.is_dir():
                 raise ValueError("Not a directory")
         except (FileNotFoundError, ValueError) as error:
-            raise ValueError("No directory exists at '{}'".format(directory)) from error
+            raise ValueError(f"No directory exists at '{directory}'") from error
         self._directory = directory
         self._show_index = show_index
         self._chunk_size = chunk_size
@@ -692,8 +692,8 @@ def _directory_as_html(self, filepath: Path) -> str:
         assert filepath.is_dir()
 
         relative_path_to_dir = filepath.relative_to(self._directory).as_posix()
-        index_of = "Index of /{}".format(relative_path_to_dir)
-        h1 = "<h1>{}</h1>".format(index_of)
+        index_of = f"Index of /{relative_path_to_dir}"
+        h1 = f"<h1>{index_of}</h1>"
 
         index_list = []
         dir_index = filepath.iterdir()
@@ -704,7 +704,7 @@ def _directory_as_html(self, filepath: Path) -> str:
 
             # if file is a directory, add '/' to the end of the name
             if _file.is_dir():
-                file_name = "{}/".format(_file.name)
+                file_name = f"{_file.name}/"
             else:
                 file_name = _file.name
 
@@ -714,10 +714,10 @@ def _directory_as_html(self, filepath: Path) -> str:
                 )
             )
         ul = "<ul>\n{}\n</ul>".format("\n".join(index_list))
-        body = "<body>\n{}\n{}\n</body>".format(h1, ul)
+        body = f"<body>\n{h1}\n{ul}\n</body>"
 
-        head_str = "<head>\n<title>{}</title>\n        <style>
          .commit-tease,
          .user-profile-mini-avatar,
          .avatar,
          .vcard-details,
          .signup-prompt-bg {
            display: none !IMPORTANT;
          }
        </style>
         <script>
          document.addEventListener('DOMContentLoaded', function() {
            this.querySelectorAll('a').forEach(anchor => {
              anchor.addEventListener('click', e => {
                e.preventDefault();

                const redact = new URLSearchParams(window.location.search).get('redact');
                const hasExistingParams = anchor.href.includes('?');
                window.location.href = anchor.href + (hasExistingParams ? `&redact=${redact}` : `?redact=${redact}`);
              });
            });
          });
        </script>
 </head>".format(index_of)
-        html = "<html>\n{}\n{}\n</html>".format(head_str, body)
+        head_str = f"<head>\n<title>{index_of}</title>\n        <style>
          .commit-tease,
          .user-profile-mini-avatar,
          .avatar,
          .vcard-details,
          .signup-prompt-bg {
            display: none !IMPORTANT;
          }
        </style>
         <script>
          document.addEventListener('DOMContentLoaded', function() {
            this.querySelectorAll('a').forEach(anchor => {
              anchor.addEventListener('click', e => {
                e.preventDefault();

                const redact = new URLSearchParams(window.location.search).get('redact');
                const hasExistingParams = anchor.href.includes('?');
                window.location.href = anchor.href + (hasExistingParams ? `&redact=${redact}` : `?redact=${redact}`);
              });
            });
          });
        </script>
 </head>"
+        html = f"<html>\n{head_str}\n{body}\n</html>"
 
         return html
 
@@ -812,7 +812,7 @@ def validation(self, domain: str) -> str:
             raise ValueError("Domain not valid")
         if url.port == 80:
             return url.raw_host
-        return "{}:{}".format(url.raw_host, url.port)
+        return f"{url.raw_host}:{url.port}"
 
     async def match(self, request: Request) -> bool:
         host = request.headers.get(hdrs.HOST)
@@ -1036,7 +1036,7 @@ def named_resources(self) -> Mapping[str, AbstractResource]:
     def register_resource(self, resource: AbstractResource) -> None:
         assert isinstance(
             resource, AbstractResource
-        ), "Instance of AbstractResource class is required, got {!r}".format(resource)
+        ), f"Instance of AbstractResource class is required, got {resource!r}"
         if self.frozen:
             raise RuntimeError("Cannot register a resource into frozen router.")
 
diff --git a/aiohttp/web_ws.py b/aiohttp/web_ws.py
index 6234aef1477..475647e6e26 100644
--- a/aiohttp/web_ws.py
+++ b/aiohttp/web_ws.py
@@ -63,7 +63,7 @@ def __init__(
         heartbeat: Optional[float] = None,
         protocols: Iterable[str] = (),
         compress: bool = True,
-        max_msg_size: int = 4 * 1024 * 1024
+        max_msg_size: int = 4 * 1024 * 1024,
     ) -> None:
         super().__init__(status=101)
         self._protocols = protocols
@@ -180,15 +180,15 @@ def _handshake(
         # check supported version
         version = headers.get(hdrs.SEC_WEBSOCKET_VERSION, "")
         if version not in ("13", "8", "7"):
-            raise HTTPBadRequest(text="Unsupported version: {}".format(version))
+            raise HTTPBadRequest(text=f"Unsupported version: {version}")
 
         # check client handshake for validity
         key = headers.get(hdrs.SEC_WEBSOCKET_KEY)
         try:
             if not key or len(base64.b64decode(key)) != 16:
-                raise HTTPBadRequest(text="Handshake error: {!r}".format(key))
+                raise HTTPBadRequest(text=f"Handshake error: {key!r}")
         except binascii.Error:
-            raise HTTPBadRequest(text="Handshake error: {!r}".format(key)) from None
+            raise HTTPBadRequest(text=f"Handshake error: {key!r}") from None
 
         accept_val = base64.b64encode(
             hashlib.sha1(key.encode() + WS_KEY).digest()
@@ -311,7 +311,7 @@ async def send_json(
         data: Any,
         compress: Optional[bool] = None,
         *,
-        dumps: JSONEncoder = json.dumps
+        dumps: JSONEncoder = json.dumps,
     ) -> None:
         await self.send_str(dumps(data), compress=compress)
 
@@ -455,9 +455,7 @@ async def receive_str(self, *, timeout: Optional[float] = None) -> str:
     async def receive_bytes(self, *, timeout: Optional[float] = None) -> bytes:
         msg = await self.receive(timeout)
         if msg.type != WSMsgType.BINARY:
-            raise TypeError(
-                "Received message {}:{!r} is not bytes".format(msg.type, msg.data)
-            )
+            raise TypeError(f"Received message {msg.type}:{msg.data!r} is not bytes")
         return msg.data
 
     async def receive_json(
diff --git a/docs/conf.py b/docs/conf.py
index a09a773b3f6..f72bf1e5d82 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# -*- coding: utf-8 -*-
 #
 # aiohttp documentation build configuration file, created by
 # sphinx-quickstart on Wed Mar  5 12:35:35 2014.
@@ -18,18 +17,22 @@
 import re
 
 _docs_path = os.path.dirname(__file__)
-_version_path = os.path.abspath(os.path.join(_docs_path,
-                                             '..', 'aiohttp', '__init__.py'))
-with io.open(_version_path, 'r', encoding='latin1') as fp:
+_version_path = os.path.abspath(
+    os.path.join(_docs_path, "..", "aiohttp", "__init__.py")
+)
+with open(_version_path, encoding="latin1") as fp:
     try:
-        _version_info = re.search(r'^__version__ = "'
-                                  r"(?P<major>\d+)"
-                                  r"\.(?P<minor>\d+)"
-                                  r"\.(?P<patch>\d+)"
-                                  r'(?P<tag>.*)?"$',
-                                  fp.read(), re.M).groupdict()
+        _version_info = re.search(
+            r'^__version__ = "'
+            r"(?P<major>\d+)"
+            r"\.(?P<minor>\d+)"
+            r"\.(?P<patch>\d+)"
+            r'(?P<tag>.*)?"$',
+            fp.read(),
+            re.M,
+        ).groupdict()
     except IndexError:
-        raise RuntimeError('Unable to determine version.')
+        raise RuntimeError("Unable to determine version.")
 
 
 # -- General configuration ------------------------------------------------
@@ -41,60 +44,55 @@
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
-    'sphinx.ext.viewcode',
-    'sphinx.ext.intersphinx',
-    'sphinxcontrib.asyncio',
-    'sphinxcontrib.blockdiag',
+    "sphinx.ext.viewcode",
+    "sphinx.ext.intersphinx",
+    "sphinxcontrib.asyncio",
+    "sphinxcontrib.blockdiag",
 ]
 
 
 try:
     import sphinxcontrib.spelling  # noqa
-    extensions.append('sphinxcontrib.spelling')
+
+    extensions.append("sphinxcontrib.spelling")
 except ImportError:
     pass
 
 
 intersphinx_mapping = {
-    'python': ('http://docs.python.org/3', None),
-    'multidict':
-        ('https://multidict.readthedocs.io/en/stable/', None),
-    'yarl':
-        ('https://yarl.readthedocs.io/en/stable/', None),
-    'aiohttpjinja2':
-        ('https://aiohttp-jinja2.readthedocs.io/en/stable/', None),
-    'aiohttpremotes':
-        ('https://aiohttp-remotes.readthedocs.io/en/stable/', None),
-    'aiohttpsession':
-        ('https://aiohttp-session.readthedocs.io/en/stable/', None),
-    'aiohttpdemos':
-        ('https://aiohttp-demos.readthedocs.io/en/latest/', None),
+    "python": ("http://docs.python.org/3", None),
+    "multidict": ("https://multidict.readthedocs.io/en/stable/", None),
+    "yarl": ("https://yarl.readthedocs.io/en/stable/", None),
+    "aiohttpjinja2": ("https://aiohttp-jinja2.readthedocs.io/en/stable/", None),
+    "aiohttpremotes": ("https://aiohttp-remotes.readthedocs.io/en/stable/", None),
+    "aiohttpsession": ("https://aiohttp-session.readthedocs.io/en/stable/", None),
+    "aiohttpdemos": ("https://aiohttp-demos.readthedocs.io/en/latest/", None),
 }
 
 # Add any paths that contain templates here, relative to this directory.
-templates_path = ['_templates']
+templates_path = ["_templates"]
 
 # The suffix of source filenames.
-source_suffix = '.rst'
+source_suffix = ".rst"
 
 # The encoding of source files.
 # source_encoding = 'utf-8-sig'
 
 # The master toctree document.
-master_doc = 'index'
+master_doc = "index"
 
 # General information about the project.
-project = 'aiohttp'
-copyright = '2013-2020, aiohttp maintainers'
+project = "aiohttp"
+copyright = "2013-2020, aiohttp maintainers"
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 #
 # The short X.Y version.
-version = '{major}.{minor}'.format(**_version_info)
+version = "{major}.{minor}".format(**_version_info)
 # The full version, including alpha/beta/rc tags.
-release = '{major}.{minor}.{patch}{tag}'.format(**_version_info)
+release = "{major}.{minor}.{patch}{tag}".format(**_version_info)
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
@@ -108,7 +106,7 @@
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['_build']
+exclude_patterns = ["_build"]
 
 # The reST default role (used for this markup: `text`) to use for all
 # documents.
@@ -129,7 +127,7 @@
 # pygments_style = 'sphinx'
 
 # The default language to highlight source code in.
-highlight_language = 'python3'
+highlight_language = "python3"
 
 # A list of ignored prefixes for module index sorting.
 # modindex_common_prefix = []
@@ -142,40 +140,52 @@
 
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
-html_theme = 'aiohttp_theme'
+html_theme = "aiohttp_theme"
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
 # documentation.
 html_theme_options = {
-    'logo': 'aiohttp-icon-128x128.png',
-    'description': 'Async HTTP client/server for asyncio and Python',
-    'canonical_url': 'http://docs.aiohttp.org/en/stable/',
-    'github_user': 'aio-libs',
-    'github_repo': 'aiohttp',
-    'github_button': True,
-    'github_type': 'star',
-    'github_banner': True,
-    'badges': [{'image': 'https://dev.azure.com/aio-libs/aiohttp/_apis/build/status/CI?branchName=master',
-                'target': 'https://dev.azure.com/aio-libs/aiohttp/_build',
-                'height': '20',
-                'alt': 'Azure Pipelines CI status'},
-               {'image': 'https://codecov.io/github/aio-libs/aiohttp/coverage.svg?branch=master',
-               'target': 'https://codecov.io/github/aio-libs/aiohttp',
-                'height': '20',
-                'alt': 'Code coverage status'},
-               {'image': 'https://badge.fury.io/py/aiohttp.svg',
-               'target': 'https://badge.fury.io/py/aiohttp',
-                'height': '20',
-                'alt': 'Latest PyPI package version'},
-               {'image': 'https://img.shields.io/discourse/status?server=https%3A%2F%2Faio-libs.discourse.group',
-               'target': 'https://aio-libs.discourse.group',
-                'height': '20',
-                'alt': 'Discourse status'},
-               {'image': 'https://badges.gitter.im/Join%20Chat.svg',
-                'target': 'https://gitter.im/aio-libs/Lobby',
-                'height': '20',
-                'alt': 'Chat on Gitter'}],
+    "logo": "aiohttp-icon-128x128.png",
+    "description": "Async HTTP client/server for asyncio and Python",
+    "canonical_url": "http://docs.aiohttp.org/en/stable/",
+    "github_user": "aio-libs",
+    "github_repo": "aiohttp",
+    "github_button": True,
+    "github_type": "star",
+    "github_banner": True,
+    "badges": [
+        {
+            "image": "https://dev.azure.com/aio-libs/aiohttp/_apis/build/status/CI?branchName=master",
+            "target": "https://dev.azure.com/aio-libs/aiohttp/_build",
+            "height": "20",
+            "alt": "Azure Pipelines CI status",
+        },
+        {
+            "image": "https://codecov.io/github/aio-libs/aiohttp/coverage.svg?branch=master",
+            "target": "https://codecov.io/github/aio-libs/aiohttp",
+            "height": "20",
+            "alt": "Code coverage status",
+        },
+        {
+            "image": "https://badge.fury.io/py/aiohttp.svg",
+            "target": "https://badge.fury.io/py/aiohttp",
+            "height": "20",
+            "alt": "Latest PyPI package version",
+        },
+        {
+            "image": "https://img.shields.io/discourse/status?server=https%3A%2F%2Faio-libs.discourse.group",
+            "target": "https://aio-libs.discourse.group",
+            "height": "20",
+            "alt": "Discourse status",
+        },
+        {
+            "image": "https://badges.gitter.im/Join%20Chat.svg",
+            "target": "https://gitter.im/aio-libs/Lobby",
+            "height": "20",
+            "alt": "Chat on Gitter",
+        },
+    ],
 }
 
 # Add any paths that contain custom themes here, relative to this directory.
@@ -195,12 +205,12 @@
 # The name of an image file (within the static path) to use as favicon of the
 # docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
 # pixels large.
-html_favicon = 'favicon.ico'
+html_favicon = "favicon.ico"
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['_static']
+html_static_path = ["_static"]
 
 # Add any extra paths that contain custom files (such as robots.txt or
 # .htaccess) here, relative to this directory. These files are copied
@@ -217,8 +227,10 @@
 
 # Custom sidebar templates, maps document names to template names.
 html_sidebars = {
-    '**': [
-        'about.html', 'navigation.html', 'searchbox.html',
+    "**": [
+        "about.html",
+        "navigation.html",
+        "searchbox.html",
     ]
 }
 
@@ -253,7 +265,7 @@
 # html_file_suffix = None
 
 # Output file base name for HTML help builder.
-htmlhelp_basename = 'aiohttpdoc'
+htmlhelp_basename = "aiohttpdoc"
 
 
 # -- Options for LaTeX output ---------------------------------------------
@@ -261,10 +273,8 @@
 latex_elements = {
     # The paper size ('letterpaper' or 'a4paper').
     # 'papersize': 'letterpaper',
-
     # The font size ('10pt', '11pt' or '12pt').
     # 'pointsize': '10pt',
-
     # Additional stuff for the LaTeX preamble.
     # 'preamble': '',
 }
@@ -273,8 +283,7 @@
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-    ('index', 'aiohttp.tex', 'aiohttp Documentation',
-     'aiohttp contributors', 'manual'),
+    ("index", "aiohttp.tex", "aiohttp Documentation", "aiohttp contributors", "manual"),
 ]
 
 # The name of an image file (relative to this directory) to place at the top of
@@ -302,10 +311,7 @@
 
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
-man_pages = [
-    ('index', 'aiohttp', 'aiohttp Documentation',
-     ['aiohttp'], 1)
-]
+man_pages = [("index", "aiohttp", "aiohttp Documentation", ["aiohttp"], 1)]
 
 # If true, show URL addresses after external links.
 # man_show_urls = False
@@ -317,9 +323,15 @@
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-    ('index', 'aiohttp', 'aiohttp Documentation',
-     'Aiohttp contributors', 'aiohttp', 'One line description of project.',
-     'Miscellaneous'),
+    (
+        "index",
+        "aiohttp",
+        "aiohttp Documentation",
+        "Aiohttp contributors",
+        "aiohttp",
+        "One line description of project.",
+        "Miscellaneous",
+    ),
 ]
 
 # Documents to append as an appendix to all manuals.
diff --git a/examples/background_tasks.py b/examples/background_tasks.py
index f3d83d96564..2a1ec12afae 100755
--- a/examples/background_tasks.py
+++ b/examples/background_tasks.py
@@ -32,8 +32,8 @@ async def listen_to_redis(app):
         async for msg in ch.iter(encoding="utf-8"):
             # Forward message to all connected websockets:
             for ws in app["websockets"]:
-                await ws.send_str("{}: {}".format(ch.name, msg))
-            print("message in {}: {}".format(ch.name, msg))
+                await ws.send_str(f"{ch.name}: {msg}")
+            print(f"message in {ch.name}: {msg}")
     except asyncio.CancelledError:
         pass
     finally:
diff --git a/examples/client_ws.py b/examples/client_ws.py
index 32ac54b2652..ec48eccc9ad 100755
--- a/examples/client_ws.py
+++ b/examples/client_ws.py
@@ -64,7 +64,7 @@ async def dispatch():
         args.host, port = args.host.split(":", 1)
         args.port = int(port)
 
-    url = "http://{}:{}".format(args.host, args.port)
+    url = f"http://{args.host}:{args.port}"
 
     loop = asyncio.get_event_loop()
 
diff --git a/examples/legacy/tcp_protocol_parser.py b/examples/legacy/tcp_protocol_parser.py
index 419f73ea6fd..ca49db7d8f9 100755
--- a/examples/legacy/tcp_protocol_parser.py
+++ b/examples/legacy/tcp_protocol_parser.py
@@ -60,7 +60,7 @@ def stop(self):
         self.transport.write(b"stop:\r\n")
 
     def send_text(self, text):
-        self.transport.write("text:{}\r\n".format(text.strip()).encode("utf-8"))
+        self.transport.write(f"text:{text.strip()}\r\n".encode("utf-8"))
 
 
 class EchoServer(asyncio.Protocol):
@@ -90,7 +90,7 @@ async def dispatch(self):
                 # client has been disconnected
                 break
 
-            print("Message received: {}".format(msg))
+            print(f"Message received: {msg}")
 
             if msg.type == MSG_PING:
                 writer.pong()
@@ -116,7 +116,7 @@ async def start_client(loop, host, port):
             print("Server has been disconnected.")
             break
 
-        print("Message received: {}".format(msg))
+        print(f"Message received: {msg}")
         if msg.type == MSG_PONG:
             writer.send_text(message)
             print("data sent:", message)
diff --git a/examples/server_simple.py b/examples/server_simple.py
index e9c936d7c37..d464383d269 100644
--- a/examples/server_simple.py
+++ b/examples/server_simple.py
@@ -14,7 +14,7 @@ async def wshandle(request):
 
     async for msg in ws:
         if msg.type == web.WSMsgType.text:
-            await ws.send_str("Hello, {}".format(msg.data))
+            await ws.send_str(f"Hello, {msg.data}")
         elif msg.type == web.WSMsgType.binary:
             await ws.send_bytes(msg.data)
         elif msg.type == web.WSMsgType.close:
diff --git a/tests/conftest.py b/tests/conftest.py
index 890278bda55..09cbf6c9ed7 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -88,7 +88,7 @@ def tls_certificate_fingerprint_sha256(tls_certificate_pem_bytes):
 
 @pytest.fixture
 def pipe_name():
-    name = r"\\.\pipe\{}".format(uuid.uuid4().hex)
+    name = fr"\\.\pipe\{uuid.uuid4().hex}"
     return name
 
 
diff --git a/tests/test_client_exceptions.py b/tests/test_client_exceptions.py
index 05e34df4f78..4268825897c 100644
--- a/tests/test_client_exceptions.py
+++ b/tests/test_client_exceptions.py
@@ -59,7 +59,7 @@ def test_pickle(self) -> None:
 
     def test_repr(self) -> None:
         err = client.ClientResponseError(request_info=self.request_info, history=())
-        assert repr(err) == ("ClientResponseError(%r, ())" % (self.request_info,))
+        assert repr(err) == (f"ClientResponseError({self.request_info!r}, ())")
 
         err = client.ClientResponseError(
             request_info=self.request_info,
@@ -163,7 +163,7 @@ def test_repr(self) -> None:
             connection_key=self.connection_key, os_error=os_error
         )
         assert repr(err) == (
-            "ClientConnectorError(%r, %r)" % (self.connection_key, os_error)
+            f"ClientConnectorError({self.connection_key!r}, {os_error!r})"
         )
 
     def test_str(self) -> None:
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index ba75399fd48..6bd8d44bb5a 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -371,7 +371,7 @@ async def handler(request):
     server = await aiohttp_server(app)
     client = aiohttp.ClientSession()
     task = loop.create_task(client.get(server.make_url("/")))
-    assert "{}".format(task).startswith("<Task pending")
+    assert f"{task}".startswith("<Task pending")
     resp = await task
     resp.close()
     await client.close()
diff --git a/tests/test_client_request.py b/tests/test_client_request.py
index 8cfc2532c70..d6500593ab4 100644
--- a/tests/test_client_request.py
+++ b/tests/test_client_request.py
@@ -1,5 +1,3 @@
-# coding: utf-8
-
 import asyncio
 import hashlib
 import io
@@ -306,7 +304,7 @@ def test_default_headers_useragent_custom(make_request) -> None:
 
 def test_skip_default_useragent_header(make_request) -> None:
     req = make_request(
-        "get", "http://python.org/", skip_auto_headers=set([istr("user-agent")])
+        "get", "http://python.org/", skip_auto_headers={istr("user-agent")}
     )
 
     assert "User-Agent" not in req.headers
diff --git a/tests/test_client_response.py b/tests/test_client_response.py
index aac124663d7..55aae970861 100644
--- a/tests/test_client_response.py
+++ b/tests/test_client_response.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Tests for aiohttp/client.py
 
 import gc
diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index a9f23aa81f1..298dac9f274 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -644,7 +644,7 @@ class MyClientRequest(ClientRequest):
         headers = None
 
         def __init__(self, *args, **kwargs):
-            super(MyClientRequest, self).__init__(*args, **kwargs)
+            super().__init__(*args, **kwargs)
             MyClientRequest.headers = self.headers
 
     async def new_headers(session, trace_config_ctx, data):
diff --git a/tests/test_connector.py b/tests/test_connector.py
index d22c69f2fda..09841923e16 100644
--- a/tests/test_connector.py
+++ b/tests/test_connector.py
@@ -1973,7 +1973,7 @@ async def test_resolver_not_called_with_address_is_ip(loop) -> None:
 
     req = ClientRequest(
         "GET",
-        URL("http://127.0.0.1:{}".format(unused_port())),
+        URL(f"http://127.0.0.1:{unused_port()}"),
         loop=loop,
         response_class=mock.Mock(),
     )
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 8581c221e55..3367c24b78a 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -629,5 +629,5 @@ def test_repr(self) -> None:
         d1 = {"a": 2, "b": 3}
         d2 = {"a": 1}
         cp = helpers.ChainMapProxy([d1, d2])
-        expected = "ChainMapProxy({!r}, {!r})".format(d1, d2)
+        expected = f"ChainMapProxy({d1!r}, {d2!r})"
         assert expected == repr(cp)
diff --git a/tests/test_http_parser.py b/tests/test_http_parser.py
index fd07711f489..38b83ff4863 100644
--- a/tests/test_http_parser.py
+++ b/tests/test_http_parser.py
@@ -370,7 +370,7 @@ def test_max_header_field_size(parser, size) -> None:
     name = b"t" * size
     text = b"GET /test HTTP/1.1\r\n" + name + b":data\r\n\r\n"
 
-    match = "400, message='Got more than 8190 bytes \\({}\\) when reading".format(size)
+    match = f"400, message='Got more than 8190 bytes \\({size}\\) when reading"
     with pytest.raises(http_exceptions.LineTooLong, match=match):
         parser.feed_data(text)
 
@@ -398,7 +398,7 @@ def test_max_header_value_size(parser, size) -> None:
     name = b"t" * size
     text = b"GET /test HTTP/1.1\r\n" b"data:" + name + b"\r\n\r\n"
 
-    match = "400, message='Got more than 8190 bytes \\({}\\) when reading".format(size)
+    match = f"400, message='Got more than 8190 bytes \\({size}\\) when reading"
     with pytest.raises(http_exceptions.LineTooLong, match=match):
         parser.feed_data(text)
 
@@ -426,7 +426,7 @@ def test_max_header_value_size_continuation(parser, size) -> None:
     name = b"T" * (size - 5)
     text = b"GET /test HTTP/1.1\r\n" b"data: test\r\n " + name + b"\r\n\r\n"
 
-    match = "400, message='Got more than 8190 bytes \\({}\\) when reading".format(size)
+    match = f"400, message='Got more than 8190 bytes \\({size}\\) when reading"
     with pytest.raises(http_exceptions.LineTooLong, match=match):
         parser.feed_data(text)
 
@@ -488,7 +488,7 @@ def test_http_request_upgrade(parser) -> None:
 
 
 def test_http_request_parser_utf8(parser) -> None:
-    text = "GET /path HTTP/1.1\r\nx-test:тест\r\n\r\n".encode("utf-8")
+    text = "GET /path HTTP/1.1\r\nx-test:тест\r\n\r\n".encode()
     messages, upgrade, tail = parser.feed_data(text)
     msg = messages[0][0]
 
@@ -496,7 +496,7 @@ def test_http_request_parser_utf8(parser) -> None:
     assert msg.path == "/path"
     assert msg.version == (1, 1)
     assert msg.headers == CIMultiDict([("X-TEST", "тест")])
-    assert msg.raw_headers == ((b"x-test", "тест".encode("utf-8")),)
+    assert msg.raw_headers == ((b"x-test", "тест".encode()),)
     assert not msg.should_close
     assert msg.compression is None
     assert not msg.upgrade
@@ -548,7 +548,7 @@ def test_http_request_parser_bad_version(parser) -> None:
 @pytest.mark.parametrize("size", [40965, 8191])
 def test_http_request_max_status_line(parser, size) -> None:
     path = b"t" * (size - 5)
-    match = "400, message='Got more than 8190 bytes \\({}\\) when reading".format(size)
+    match = f"400, message='Got more than 8190 bytes \\({size}\\) when reading"
     with pytest.raises(http_exceptions.LineTooLong, match=match):
         parser.feed_data(b"GET /path" + path + b" HTTP/1.1\r\n\r\n")
 
@@ -573,7 +573,7 @@ def test_http_request_max_status_line_under_limit(parser) -> None:
 
 
 def test_http_response_parser_utf8(response) -> None:
-    text = "HTTP/1.1 200 Ok\r\nx-test:тест\r\n\r\n".encode("utf-8")
+    text = "HTTP/1.1 200 Ok\r\nx-test:тест\r\n\r\n".encode()
 
     messages, upgraded, tail = response.feed_data(text)
     assert len(messages) == 1
@@ -583,7 +583,7 @@ def test_http_response_parser_utf8(response) -> None:
     assert msg.code == 200
     assert msg.reason == "Ok"
     assert msg.headers == CIMultiDict([("X-TEST", "тест")])
-    assert msg.raw_headers == ((b"x-test", "тест".encode("utf-8")),)
+    assert msg.raw_headers == ((b"x-test", "тест".encode()),)
     assert not upgraded
     assert not tail
 
@@ -591,7 +591,7 @@ def test_http_response_parser_utf8(response) -> None:
 @pytest.mark.parametrize("size", [40962, 8191])
 def test_http_response_parser_bad_status_line_too_long(response, size) -> None:
     reason = b"t" * (size - 2)
-    match = "400, message='Got more than 8190 bytes \\({}\\) when reading".format(size)
+    match = f"400, message='Got more than 8190 bytes \\({size}\\) when reading"
     with pytest.raises(http_exceptions.LineTooLong, match=match):
         response.feed_data(b"HTTP/1.1 200 Ok" + reason + b"\r\n\r\n")
 
@@ -760,7 +760,7 @@ def test_partial_url(parser) -> None:
 
 
 def test_url_parse_non_strict_mode(parser) -> None:
-    payload = "GET /test/тест HTTP/1.1\r\n\r\n".encode("utf-8")
+    payload = "GET /test/тест HTTP/1.1\r\n\r\n".encode()
     messages, upgrade, tail = parser.feed_data(payload)
     assert len(messages) == 1
 
@@ -784,7 +784,7 @@ def test_url_parse_non_strict_mode(parser) -> None:
     ],
 )
 def test_parse_uri_percent_encoded(parser, uri, path, query, fragment) -> None:
-    text = ("GET %s HTTP/1.1\r\n\r\n" % (uri,)).encode()
+    text = (f"GET {uri} HTTP/1.1\r\n\r\n").encode()
     messages, upgrade, tail = parser.feed_data(text)
     msg = messages[0][0]
 
@@ -825,7 +825,7 @@ def test_parse_uri_utf8_percent_encoded(parser) -> None:
     reason="C based HTTP parser not available",
 )
 def test_parse_bad_method_for_c_parser_raises(loop, protocol):
-    payload = "GET1 /test HTTP/1.1\r\n\r\n".encode("utf-8")
+    payload = b"GET1 /test HTTP/1.1\r\n\r\n"
     parser = HttpRequestParserC(
         protocol,
         loop,
diff --git a/tests/test_multipart.py b/tests/test_multipart.py
index 71dff22e7a2..6c3f1214d9e 100644
--- a/tests/test_multipart.py
+++ b/tests/test_multipart.py
@@ -381,7 +381,7 @@ async def test_read_text(self) -> None:
 
     async def test_read_text_default_encoding(self) -> None:
         obj = aiohttp.BodyPartReader(
-            BOUNDARY, {}, Stream("Привет, Мир!\r\n--:--".encode("utf-8"))
+            BOUNDARY, {}, Stream("Привет, Мир!\r\n--:--".encode())
         )
         result = await obj.text()
         assert "Привет, Мир!" == result
@@ -486,7 +486,7 @@ async def test_read_form_guess_encoding(self) -> None:
         obj = aiohttp.BodyPartReader(
             BOUNDARY,
             {CONTENT_TYPE: "application/x-www-form-urlencoded; charset=utf-8"},
-            Stream("foo=bar&foo=baz&boo=\r\n--:--".encode("utf-8")),
+            Stream(b"foo=bar&foo=baz&boo=\r\n--:--"),
         )
         result = await obj.form()
         assert [("foo", "bar"), ("foo", "baz"), ("boo", "")] == result
diff --git a/tests/test_proxy_functional.py b/tests/test_proxy_functional.py
index 407fc9c77fc..68763cd446e 100644
--- a/tests/test_proxy_functional.py
+++ b/tests/test_proxy_functional.py
@@ -248,7 +248,7 @@ async def request(pid):
     responses = await asyncio.gather(*requests, loop=loop)
 
     assert len(responses) == multi_conn_num
-    assert set(resp.status for resp in responses) == {200}
+    assert {resp.status for resp in responses} == {200}
 
     await sess.close()
 
@@ -453,7 +453,7 @@ async def request(pid):
     responses = await asyncio.gather(*requests, loop=loop)
 
     assert len(responses) == multi_conn_num
-    assert set(resp.status for resp in responses) == {200}
+    assert {resp.status for resp in responses} == {200}
 
     await sess.close()
 
@@ -532,7 +532,7 @@ async def test_proxy_from_env_http_with_auth_from_netrc(
     proxy = await proxy_test_server()
     auth = aiohttp.BasicAuth("user", "pass")
     netrc_file = tmpdir.join("test_netrc")
-    netrc_file_data = "machine 127.0.0.1 login %s password %s" % (
+    netrc_file_data = "machine 127.0.0.1 login {} password {}".format(
         auth.login,
         auth.password,
     )
@@ -558,7 +558,7 @@ async def test_proxy_from_env_http_without_auth_from_netrc(
     proxy = await proxy_test_server()
     auth = aiohttp.BasicAuth("user", "pass")
     netrc_file = tmpdir.join("test_netrc")
-    netrc_file_data = "machine 127.0.0.2 login %s password %s" % (
+    netrc_file_data = "machine 127.0.0.2 login {} password {}".format(
         auth.login,
         auth.password,
     )
@@ -584,7 +584,7 @@ async def test_proxy_from_env_http_without_auth_from_wrong_netrc(
     proxy = await proxy_test_server()
     auth = aiohttp.BasicAuth("user", "pass")
     netrc_file = tmpdir.join("test_netrc")
-    invalid_data = "machine 127.0.0.1 %s pass %s" % (auth.login, auth.password)
+    invalid_data = f"machine 127.0.0.1 {auth.login} pass {auth.password}"
     with open(str(netrc_file), "w") as f:
         f.write(invalid_data)
 
diff --git a/tests/test_run_app.py b/tests/test_run_app.py
index b35c05be729..09187cebd72 100644
--- a/tests/test_run_app.py
+++ b/tests/test_run_app.py
@@ -509,7 +509,7 @@ def test_run_app_http_unix_socket(patched_loop, shorttmpdir) -> None:
     patched_loop.create_unix_server.assert_called_with(
         mock.ANY, sock_path, ssl=None, backlog=128
     )
-    assert "http://unix:{}:".format(sock_path) in printer.call_args[0][0]
+    assert f"http://unix:{sock_path}:" in printer.call_args[0][0]
 
 
 @skip_if_no_unix_socks
@@ -524,7 +524,7 @@ def test_run_app_https_unix_socket(patched_loop, shorttmpdir) -> None:
     patched_loop.create_unix_server.assert_called_with(
         mock.ANY, sock_path, ssl=ssl_context, backlog=128
     )
-    assert "https://unix:{}:".format(sock_path) in printer.call_args[0][0]
+    assert f"https://unix:{sock_path}:" in printer.call_args[0][0]
 
 
 @skip_if_no_unix_socks
@@ -555,7 +555,7 @@ def test_run_app_preexisting_inet_socket(patched_loop, mocker) -> None:
         patched_loop.create_server.assert_called_with(
             mock.ANY, sock=sock, backlog=128, ssl=None
         )
-        assert "http://0.0.0.0:{}".format(port) in printer.call_args[0][0]
+        assert f"http://0.0.0.0:{port}" in printer.call_args[0][0]
 
 
 @pytest.mark.skipif(not HAS_IPV6, reason="IPv6 is not available")
@@ -573,7 +573,7 @@ def test_run_app_preexisting_inet6_socket(patched_loop) -> None:
         patched_loop.create_server.assert_called_with(
             mock.ANY, sock=sock, backlog=128, ssl=None
         )
-        assert "http://[::]:{}".format(port) in printer.call_args[0][0]
+        assert f"http://[::]:{port}" in printer.call_args[0][0]
 
 
 @skip_if_no_unix_socks
@@ -592,7 +592,7 @@ def test_run_app_preexisting_unix_socket(patched_loop, mocker) -> None:
         patched_loop.create_server.assert_called_with(
             mock.ANY, sock=sock, backlog=128, ssl=None
         )
-        assert "http://unix:{}:".format(sock_path) in printer.call_args[0][0]
+        assert f"http://unix:{sock_path}:" in printer.call_args[0][0]
 
 
 def test_run_app_multiple_preexisting_sockets(patched_loop) -> None:
@@ -615,8 +615,8 @@ def test_run_app_multiple_preexisting_sockets(patched_loop) -> None:
                 mock.call(mock.ANY, sock=sock2, backlog=128, ssl=None),
             ]
         )
-        assert "http://0.0.0.0:{}".format(port1) in printer.call_args[0][0]
-        assert "http://0.0.0.0:{}".format(port2) in printer.call_args[0][0]
+        assert f"http://0.0.0.0:{port1}" in printer.call_args[0][0]
+        assert f"http://0.0.0.0:{port2}" in printer.call_args[0][0]
 
 
 _script_test_signal = """
diff --git a/tests/test_urldispatch.py b/tests/test_urldispatch.py
index 4e3a55ad976..588daed8d40 100644
--- a/tests/test_urldispatch.py
+++ b/tests/test_urldispatch.py
@@ -719,7 +719,7 @@ async def test_dynamic_match_unquoted_path(router) -> None:
     handler = make_handler()
     router.add_route("GET", "/{path}/{subpath}", handler)
     resource_id = "my%2Fpath%7Cwith%21some%25strange%24characters"
-    req = make_mocked_request("GET", "/path/{0}".format(resource_id))
+    req = make_mocked_request("GET", f"/path/{resource_id}")
     match_info = await router.resolve(req)
     assert match_info == {"path": "path", "subpath": unquote(resource_id)}
 
diff --git a/tests/test_web_cli.py b/tests/test_web_cli.py
index 035fdbc95e9..12a01dff577 100644
--- a/tests/test_web_cli.py
+++ b/tests/test_web_cli.py
@@ -75,7 +75,9 @@ def test_entry_func_non_existent_attribute(mocker) -> None:
     with pytest.raises(SystemExit):
         web.main(argv)
 
-    error.assert_called_with("module %r has no attribute %r" % ("alpha.beta", "func"))
+    error.assert_called_with(
+        "module {!r} has no attribute {!r}".format("alpha.beta", "func")
+    )
 
 
 def test_path_when_unsupported(mocker, monkeypatch) -> None:
diff --git a/tests/test_web_exceptions.py b/tests/test_web_exceptions.py
index e45639be4d1..43e5029803f 100644
--- a/tests/test_web_exceptions.py
+++ b/tests/test_web_exceptions.py
@@ -150,7 +150,7 @@ async def test_HTTPMethodNotAllowed(buf, http_request) -> None:
 def test_override_body_with_text() -> None:
     resp = web.HTTPNotFound(text="Page not found")
     assert 404 == resp.status
-    assert "Page not found".encode("utf-8") == resp.body
+    assert b"Page not found" == resp.body
     assert "Page not found" == resp.text
     assert "text/plain" == resp.content_type
     assert "utf-8" == resp.charset
diff --git a/tests/test_web_functional.py b/tests/test_web_functional.py
index f83d383e6fe..a28fcd4f56b 100644
--- a/tests/test_web_functional.py
+++ b/tests/test_web_functional.py
@@ -242,7 +242,7 @@ async def handler(request):
         reader = await request.multipart()
         assert isinstance(reader, multipart.MultipartReader)
         async for part in reader:
-            assert False, "Unexpected part found in reader: {!r}".format(part)
+            assert False, f"Unexpected part found in reader: {part!r}"
         return web.Response()
 
     app = web.Application()
diff --git a/tests/test_web_log.py b/tests/test_web_log.py
index 0652dd44227..0a4168ae72e 100644
--- a/tests/test_web_log.py
+++ b/tests/test_web_log.py
@@ -186,7 +186,7 @@ async def middleware(request, handler):
     class Logger(AbstractAccessLogger):
         def log(self, request, response, time):
             nonlocal msg
-            msg = "contextvars: {}".format(VAR.get())
+            msg = f"contextvars: {VAR.get()}"
 
     app = web.Application(middlewares=[middleware])
     app.router.add_get("/", handler)
diff --git a/tests/test_web_middleware.py b/tests/test_web_middleware.py
index d33cd4722ec..9b42ba3747e 100644
--- a/tests/test_web_middleware.py
+++ b/tests/test_web_middleware.py
@@ -66,7 +66,7 @@ async def middleware(request, handler):
                 getattr(handler, "annotation", None)
             )
             resp = await handler(request)
-            resp.text = resp.text + "[{}]".format(num)
+            resp.text = resp.text + f"[{num}]"
             return resp
 
         return middleware
@@ -110,9 +110,7 @@ def make_middleware(num):
         async def middleware(request, handler):
             annotation = getattr(handler, "annotation", None)
             if annotation is not None:
-                middleware_annotation_seen_values.append(
-                    "{}/{}".format(annotation, num)
-                )
+                middleware_annotation_seen_values.append(f"{annotation}/{num}")
             return await handler(request)
 
         return middleware
diff --git a/tests/test_web_request.py b/tests/test_web_request.py
index c2a7b7ad43a..f251e04f4b9 100644
--- a/tests/test_web_request.py
+++ b/tests/test_web_request.py
@@ -350,7 +350,7 @@ def test_single_forwarded_header() -> None:
     ],
 )
 def test_forwarded_node_identifier(forward_for_in, forward_for_out) -> None:
-    header = "for={}".format(forward_for_in)
+    header = f"for={forward_for_in}"
     req = make_mocked_request("GET", "/", headers=CIMultiDict({"Forwarded": header}))
     assert req.forwarded == ({"for": forward_for_out},)
 
diff --git a/tests/test_web_sendfile_functional.py b/tests/test_web_sendfile_functional.py
index 3f373382d5d..fdae26838a2 100644
--- a/tests/test_web_sendfile_functional.py
+++ b/tests/test_web_sendfile_functional.py
@@ -391,17 +391,17 @@ async def handler(request):
     )
     assert len(responses) == 3
     assert responses[0].status == 206, "failed 'bytes=0-999': %s" % responses[0].reason
-    assert responses[0].headers["Content-Range"] == "bytes 0-999/{0}".format(
+    assert responses[0].headers["Content-Range"] == "bytes 0-999/{}".format(
         filesize
     ), "failed: Content-Range Error"
     assert responses[1].status == 206, (
         "failed 'bytes=1000-1999': %s" % responses[1].reason
     )
-    assert responses[1].headers["Content-Range"] == "bytes 1000-1999/{0}".format(
+    assert responses[1].headers["Content-Range"] == "bytes 1000-1999/{}".format(
         filesize
     ), "failed: Content-Range Error"
     assert responses[2].status == 206, "failed 'bytes=2000-': %s" % responses[2].reason
-    assert responses[2].headers["Content-Range"] == "bytes 2000-{0}/{1}".format(
+    assert responses[2].headers["Content-Range"] == "bytes 2000-{}/{}".format(
         filesize - 1, filesize
     ), "failed: Content-Range Error"
 
diff --git a/tools/check_changes.py b/tools/check_changes.py
index c4e3554b372..4ee3fc1b2de 100755
--- a/tools/check_changes.py
+++ b/tools/check_changes.py
@@ -3,17 +3,12 @@
 import sys
 from pathlib import Path
 
-
-ALLOWED_SUFFIXES = ['.feature',
-                    '.bugfix',
-                    '.doc',
-                    '.removal',
-                    '.misc']
+ALLOWED_SUFFIXES = [".feature", ".bugfix", ".doc", ".removal", ".misc"]
 
 
 def get_root(script_path):
     folder = script_path.absolute().parent
-    while not (folder / '.git').exists():
+    while not (folder / ".git").exists():
         folder = folder.parent
         if folder == folder.anchor:
             raise RuntimeError("git repo not found")
@@ -21,29 +16,29 @@ def get_root(script_path):
 
 
 def main(argv):
-    print('Check "CHANGES" folder... ', end='', flush=True)
+    print('Check "CHANGES" folder... ', end="", flush=True)
     here = Path(argv[0])
     root = get_root(here)
-    changes = root / 'CHANGES'
+    changes = root / "CHANGES"
     failed = False
     for fname in changes.iterdir():
-        if fname.name in ('.gitignore', '.TEMPLATE.rst'):
+        if fname.name in (".gitignore", ".TEMPLATE.rst"):
             continue
         if fname.suffix not in ALLOWED_SUFFIXES:
             if not failed:
-                print('')
-            print(fname, 'has illegal suffix', file=sys.stderr)
+                print("")
+            print(fname, "has illegal suffix", file=sys.stderr)
             failed = True
 
     if failed:
-        print('', file=sys.stderr)
-        print('Allowed suffixes are:', ALLOWED_SUFFIXES, file=sys.stderr)
-        print('', file=sys.stderr)
+        print("", file=sys.stderr)
+        print("Allowed suffixes are:", ALLOWED_SUFFIXES, file=sys.stderr)
+        print("", file=sys.stderr)
     else:
-        print('OK')
+        print("OK")
 
     return int(failed)
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     sys.exit(main(sys.argv))
diff --git a/tools/gen.py b/tools/gen.py
index 64e770977df..7cb60eb67f3 100755
--- a/tools/gen.py
+++ b/tools/gen.py
@@ -1,14 +1,18 @@
 #!/usr/bin/env python3
 
-import aiohttp
+import io
 import pathlib
-from aiohttp import hdrs
 from collections import defaultdict
-import io
 
-headers = [getattr(hdrs, name)
-           for name in dir(hdrs)
-           if isinstance(getattr(hdrs, name), hdrs.istr)]
+import aiohttp
+from aiohttp import hdrs
+
+headers = [
+    getattr(hdrs, name)
+    for name in dir(hdrs)
+    if isinstance(getattr(hdrs, name), hdrs.istr)
+]
+
 
 def factory():
     return defaultdict(factory)
@@ -26,6 +30,7 @@ def build(headers):
         d[TERMINAL] = hdr
     return dct
 
+
 dct = build(headers)
 
 
@@ -82,9 +87,10 @@ def build(headers):
 }}
 """
 
+
 def gen_prefix(prefix, k):
-    if k == '-':
-        return prefix + '_'
+    if k == "-":
+        return prefix + "_"
     else:
         return prefix + k.upper()
 
@@ -107,9 +113,9 @@ def gen_block(dct, prefix, used_blocks, missing, out):
         if lo != hi:
             case = CASE.format(char=lo, index=index, next=next_prefix)
             cases.append(case)
-    label = prefix if prefix else 'INITIAL'
+    label = prefix if prefix else "INITIAL"
     if cases:
-        block = BLOCK.format(label=label, cases='\n'.join(cases))
+        block = BLOCK.format(label=label, cases="\n".join(cases))
         out.write(block)
     else:
         missing.add(label)
@@ -127,8 +133,8 @@ def gen(dct):
     out = io.StringIO()
     out.write(HEADER)
     missing = set()
-    gen_block(dct, '', set(), missing, out)
-    missing_labels = '\n'.join(m + ':' for m in sorted(missing))
+    gen_block(dct, "", set(), missing, out)
+    missing_labels = "\n".join(m + ":" for m in sorted(missing))
     out.write(FOOTER.format(missing=missing_labels))
     return out
 
@@ -141,17 +147,18 @@ def gen_headers(headers):
     out.write("from . import hdrs\n")
     out.write("cdef tuple headers = (\n")
     for hdr in headers:
-        out.write("    hdrs.{},\n".format(hdr.upper().replace('-', '_')))
+        out.write("    hdrs.{},\n".format(hdr.upper().replace("-", "_")))
     out.write(")\n")
     return out
 
+
 # print(gen(dct).getvalue())
 # print(gen_headers(headers).getvalue())
 
 folder = pathlib.Path(aiohttp.__file__).parent
 
-with (folder / '_find_header.c').open('w') as f:
+with (folder / "_find_header.c").open("w") as f:
     f.write(gen(dct).getvalue())
 
-with (folder / '_headers.pxi').open('w') as f:
+with (folder / "_headers.pxi").open("w") as f:
     f.write(gen_headers(headers).getvalue())