diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 3a11f910ba..e221cfd920 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config --auto-gen-only-exclude --exclude-limit 5000`
-# on 2024-03-26 03:54:44 UTC using RuboCop version 1.59.0.
+# on 2024-04-01 12:18:08 UTC using RuboCop version 1.59.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -40,7 +40,7 @@ Lint/EmptyClass:
   Exclude:
     - 'lib/grape/dsl/parameters.rb'
 
-# Offense count: 6
+# Offense count: 5
 # Configuration parameters: AllowedParentClasses.
 Lint/MissingSuper:
   Exclude:
@@ -49,7 +49,6 @@ Lint/MissingSuper:
     - 'lib/grape/namespace.rb'
     - 'lib/grape/path.rb'
     - 'lib/grape/router/pattern.rb'
-    - 'lib/grape/validations/validators/base.rb'
 
 # Offense count: 1
 # Configuration parameters: CountComments, Max, CountAsOne, AllowedMethods, AllowedPatterns.
@@ -92,7 +91,7 @@ RSpec/AnyInstance:
     - 'spec/grape/api_spec.rb'
     - 'spec/grape/middleware/base_spec.rb'
 
-# Offense count: 2
+# Offense count: 1
 # Configuration parameters: IgnoredMetadata.
 RSpec/DescribeClass:
   Exclude:
@@ -102,7 +101,6 @@ RSpec/DescribeClass:
     - '**/spec/system/**/*'
     - '**/spec/views/**/*'
     - 'spec/grape/named_api_spec.rb'
-    - 'spec/grape/validations/instance_behaivour_spec.rb'
 
 # Offense count: 3
 # This cop supports safe autocorrection (--autocorrect).
@@ -156,7 +154,7 @@ RSpec/MessageChain:
   Exclude:
     - 'spec/grape/middleware/formatter_spec.rb'
 
-# Offense count: 148
+# Offense count: 144
 # Configuration parameters: .
 # SupportedStyles: have_received, receive
 RSpec/MessageSpies:
@@ -206,17 +204,15 @@ RSpec/RepeatedExampleGroupDescription:
     - 'spec/grape/util/inheritable_setting_spec.rb'
     - 'spec/grape/validations/validators/values_spec.rb'
 
-# Offense count: 6
+# Offense count: 2
 # This cop supports safe autocorrection (--autocorrect).
 RSpec/ScatteredSetup:
   Exclude:
     - 'spec/grape/util/inheritable_setting_spec.rb'
-    - 'spec/grape/validations_spec.rb'
 
-# Offense count: 9
+# Offense count: 8
 RSpec/StubbedMock:
   Exclude:
-    - 'spec/grape/api_spec.rb'
     - 'spec/grape/dsl/inside_route_spec.rb'
     - 'spec/grape/dsl/routing_spec.rb'
     - 'spec/grape/middleware/formatter_spec.rb'
@@ -295,7 +291,7 @@ Style/OptionalBooleanParameter:
     - 'lib/grape/validations/types/primitive_coercer.rb'
     - 'lib/grape/validations/types/set_coercer.rb'
 
-# Offense count: 28
+# Offense count: 29
 # This cop supports safe autocorrection (--autocorrect).
 Style/RedundantConstantBase:
   Exclude:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 45b5a8fe0a..96c236ec38 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@
 * [#2389](https://github.com/ruby-grape/grape/pull/2389): Remove rack-accept dependency - [@ericproulx](https://github.com/ericproulx).
 * [#2426](https://github.com/ruby-grape/grape/pull/2426): Drop support for rack 1.x series - [@ericproulx](https://github.com/ericproulx).
 * [#2427](https://github.com/ruby-grape/grape/pull/2427): Use `rack-contrib` jsonp instead of rack-jsonp - [@ericproulx](https://github.com/ericproulx).
+* [#2363](https://github.com/ruby-grape/grape/pull/2363): Replace autoload by zeitwerk - [@ericproulx](https://github.com/ericproulx).
 * Your contribution here.
 
 #### Fixes
diff --git a/UPGRADING.md b/UPGRADING.md
index d7ef9248b0..3bc1fcf312 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -3,6 +3,13 @@ Upgrading Grape
 
 ### Upgrading to >= 2.1.0
 
+#### Zeitwerk
+
+Grape's autoloader has been updated and it's now based on [Zeitwerk](https://github.com/fxn/zeitwerk).
+If you MP (Monkey Patch) some files and you're not following the [file structure](https://github.com/fxn/zeitwerk?tab=readme-ov-file#file-structure), you might end up with a Zeitwerk error.
+
+See [#2363](https://github.com/ruby-grape/grape/pull/2363) for more information.
+
 #### Changes in rescue_from
 
 The `rack_response` method has been deprecated and the `error_response` method has been removed. Use `error!` instead.
diff --git a/benchmark/compile_many_routes.rb b/benchmark/compile_many_routes.rb
index 9fa858cf37..1b273302ff 100644
--- a/benchmark/compile_many_routes.rb
+++ b/benchmark/compile_many_routes.rb
@@ -3,9 +3,6 @@
 $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
 require 'grape'
 require 'benchmark/ips'
-require 'grape/eager_load'
-
-Grape.eager_load!
 
 class API < Grape::API
   prefix :api
diff --git a/grape.gemspec b/grape.gemspec
index 1ad463c280..92c2d7fd0c 100644
--- a/grape.gemspec
+++ b/grape.gemspec
@@ -25,6 +25,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency 'dry-types', '>= 1.1'
   s.add_runtime_dependency 'mustermann-grape', '~> 1.1.0'
   s.add_runtime_dependency 'rack', '>= 2'
+  s.add_runtime_dependency 'zeitwerk'
 
   s.files = Dir['lib/**/*', 'CHANGELOG.md', 'CONTRIBUTING.md', 'README.md', 'grape.png', 'UPGRADING.md', 'LICENSE', 'grape.gemspec']
   s.require_paths = ['lib']
diff --git a/lib/grape.rb b/lib/grape.rb
index 4bfecdcb01..2c99d377a8 100644
--- a/lib/grape.rb
+++ b/lib/grape.rb
@@ -1,12 +1,5 @@
 # frozen_string_literal: true
 
-require 'logger'
-require 'rack'
-require 'rack/builder'
-require 'rack/auth/basic'
-require 'set'
-require 'bigdecimal'
-require 'date'
 require 'active_support'
 require 'active_support/concern'
 require 'active_support/configurable'
@@ -26,293 +19,54 @@
 require 'active_support/core_ext/object/blank'
 require 'active_support/core_ext/object/deep_dup'
 require 'active_support/core_ext/object/duplicable'
+require 'active_support/core_ext/string/output_safety'
 require 'active_support/core_ext/string/exclude'
-require 'active_support/dependencies/autoload'
 require 'active_support/deprecation'
 require 'active_support/inflector'
 require 'active_support/notifications'
-require 'i18n'
+
+require 'English'
+require 'bigdecimal'
+require 'date'
+require 'dry-types'
+require 'forwardable'
+require 'json'
+require 'logger'
+require 'mustermann/grape'
+require 'pathname'
+require 'rack'
+require 'rack/auth/basic'
+require 'rack/builder'
+require 'rack/head'
+require 'set'
+require 'singleton'
+require 'zeitwerk'
+
+loader = Zeitwerk::Loader.for_gem
+loader.inflector.inflect(
+  'api' => 'API',
+  'dsl' => 'DSL'
+)
+railtie = "#{__dir__}/grape/railtie.rb"
+loader.do_not_eager_load(railtie)
+loader.setup
 
 I18n.load_path << File.expand_path('grape/locale/en.yml', __dir__)
 
 module Grape
   include ActiveSupport::Configurable
-  extend ::ActiveSupport::Autoload
 
   def self.deprecator
     @deprecator ||= ActiveSupport::Deprecation.new('2.0', 'Grape')
   end
 
-  def self.lowercase_headers?
-    Rack::CONTENT_TYPE == 'content-type'
-  end
-
-  eager_autoload do
-    autoload :API
-    autoload :Endpoint
-
-    autoload :Namespace
-
-    autoload :Path
-    autoload :Cookies
-    autoload :Validations
-    autoload :ErrorFormatter
-    autoload :Formatter
-    autoload :Parser
-    autoload :Request
-    autoload :Env, 'grape/util/env'
-    autoload :Json, 'grape/util/json'
-    autoload :Xml, 'grape/util/xml'
-    autoload :DryTypes
-  end
-
-  module Http
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Headers
-    end
-  end
-
-  module Exceptions
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Base
-      autoload :Validation
-      autoload :ValidationArrayErrors
-      autoload :ValidationErrors
-      autoload :MissingVendorOption
-      autoload :MissingMimeType
-      autoload :MissingOption
-      autoload :InvalidFormatter
-      autoload :InvalidVersionerOption
-      autoload :UnknownValidator
-      autoload :UnknownOptions
-      autoload :UnknownParameter
-      autoload :InvalidWithOptionForRepresent
-      autoload :IncompatibleOptionValues
-      autoload :MissingGroupType
-      autoload :UnsupportedGroupType
-      autoload :InvalidMessageBody
-      autoload :InvalidAcceptHeader
-      autoload :InvalidVersionHeader
-      autoload :MethodNotAllowed
-      autoload :InvalidResponse
-      autoload :EmptyMessageBody
-      autoload :TooManyMultipartFiles
-      autoload :MissingGroupTypeError, 'grape/exceptions/missing_group_type'
-      autoload :UnsupportedGroupTypeError, 'grape/exceptions/unsupported_group_type'
-    end
-  end
-
-  module Extensions
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Hash
-    end
-    module ActiveSupport
-      extend ::ActiveSupport::Autoload
-      eager_autoload do
-        autoload :HashWithIndifferentAccess
-      end
-    end
-
-    module Hashie
-      extend ::ActiveSupport::Autoload
-      eager_autoload do
-        autoload :Mash
-      end
-    end
-  end
-
-  module Middleware
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Base
-      autoload :Versioner
-      autoload :Formatter
-      autoload :Error
-      autoload :Globals
-      autoload :Stack
-      autoload :Helpers
-    end
-
-    module Auth
-      extend ::ActiveSupport::Autoload
-      eager_autoload do
-        autoload :Base
-        autoload :DSL
-        autoload :StrategyInfo
-        autoload :Strategies
-      end
-    end
-
-    module Versioner
-      extend ::ActiveSupport::Autoload
-      eager_autoload do
-        autoload :Path
-        autoload :Header
-        autoload :Param
-        autoload :AcceptVersionHeader
-      end
-    end
-  end
-
-  module Util
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :InheritableValues
-      autoload :StackableValues
-      autoload :ReverseStackableValues
-      autoload :InheritableSetting
-      autoload :StrictHashConfiguration
-      autoload :Registrable
-    end
-  end
-
-  module ErrorFormatter
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Base
-      autoload :Json
-      autoload :Txt
-      autoload :Xml
-    end
-  end
-
-  module Formatter
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Json
-      autoload :SerializableHash
-      autoload :Txt
-      autoload :Xml
-    end
-  end
-
-  module Parser
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Json
-      autoload :Xml
-    end
-  end
-
-  module DSL
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :API
-      autoload :Callbacks
-      autoload :Settings
-      autoload :Configuration
-      autoload :InsideRoute
-      autoload :Helpers
-      autoload :Middleware
-      autoload :Parameters
-      autoload :RequestResponse
-      autoload :Routing
-      autoload :Validations
-      autoload :Logger
-      autoload :Desc
-    end
-  end
-
-  class API
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Helpers
-    end
-  end
-
-  module Presenters
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :Presenter
-    end
-  end
-
-  module ServeStream
-    extend ::ActiveSupport::Autoload
-    eager_autoload do
-      autoload :FileBody
-      autoload :SendfileResponse
-      autoload :StreamResponse
-    end
-  end
-
-  module Validations
-    extend ::ActiveSupport::Autoload
-
-    eager_autoload do
-      autoload :AttributesIterator
-      autoload :MultipleAttributesIterator
-      autoload :SingleAttributeIterator
-      autoload :Types
-      autoload :ParamsScope
-      autoload :ContractScope
-      autoload :ValidatorFactory
-      autoload :Base, 'grape/validations/validators/base'
-    end
-
-    module Types
-      extend ::ActiveSupport::Autoload
-
-      eager_autoload do
-        autoload :InvalidValue
-        autoload :DryTypeCoercer
-        autoload :ArrayCoercer
-        autoload :SetCoercer
-        autoload :PrimitiveCoercer
-        autoload :CustomTypeCoercer
-        autoload :CustomTypeCollectionCoercer
-        autoload :MultipleTypeCoercer
-        autoload :VariantCollectionCoercer
-      end
-    end
-
-    module Validators
-      extend ::ActiveSupport::Autoload
-
-      eager_autoload do
-        autoload :Base
-        autoload :MultipleParamsBase
-        autoload :AllOrNoneOfValidator
-        autoload :AllowBlankValidator
-        autoload :AsValidator
-        autoload :AtLeastOneOfValidator
-        autoload :CoerceValidator
-        autoload :DefaultValidator
-        autoload :ExactlyOneOfValidator
-        autoload :ExceptValuesValidator
-        autoload :MutualExclusionValidator
-        autoload :PresenceValidator
-        autoload :RegexpValidator
-        autoload :SameAsValidator
-        autoload :ValuesValidator
-      end
-    end
-  end
-
-  module Types
-    extend ::ActiveSupport::Autoload
-
-    eager_autoload do
-      autoload :InvalidValue
-    end
-  end
-
   configure do |config|
     config.param_builder = Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
     config.compile_methods!
   end
 end
 
-require 'grape/content_types'
-
-require 'grape/util/lazy_value'
-require 'grape/util/lazy_block'
-require 'grape/util/endpoint_configuration'
-require 'grape/version'
-
 # https://api.rubyonrails.org/classes/ActiveSupport/Deprecation.html
 # adding Grape.deprecator to Rails App if any
 require 'grape/railtie' if defined?(Rails::Railtie) && ActiveSupport.gem_version >= Gem::Version.new('7.1')
+loader.eager_load
diff --git a/lib/grape/api.rb b/lib/grape/api.rb
index 536d997e9f..38f17dcc56 100644
--- a/lib/grape/api.rb
+++ b/lib/grape/api.rb
@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/router'
-require 'grape/api/instance'
-
 module Grape
   # The API class is the primary entry point for creating Grape APIs. Users
   # should subclass this class in order to build an API.
@@ -128,7 +125,6 @@ def method_missing(method, *args, &block)
       end
 
       def compile!
-        require 'grape/eager_load'
         instance_for_rack.compile! # See API::Instance.compile!
       end
 
diff --git a/lib/grape/api/instance.rb b/lib/grape/api/instance.rb
index a326f44c6e..c0c6ba2fd5 100644
--- a/lib/grape/api/instance.rb
+++ b/lib/grape/api/instance.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/router'
-
 module Grape
   class API
     # The API Instance class, is the engine behind Grape::API. Each class that inherits
@@ -112,7 +110,7 @@ def nest(*blocks, &block)
         end
 
         def evaluate_as_instance_with_configuration(block, lazy: false)
-          lazy_block = Grape::Util::LazyBlock.new do |configuration|
+          lazy_block = Grape::Util::Lazy::Block.new do |configuration|
             value_for_configuration = configuration
             self.configuration = value_for_configuration.evaluate if value_for_configuration.respond_to?(:lazy?) && value_for_configuration.lazy?
             response = instance_eval(&block)
diff --git a/lib/grape/content_types.rb b/lib/grape/content_types.rb
index c6f295154a..cc0cc2cab1 100644
--- a/lib/grape/content_types.rb
+++ b/lib/grape/content_types.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/util/registrable'
-
 module Grape
   module ContentTypes
     extend Util::Registrable
diff --git a/lib/grape/dry_types.rb b/lib/grape/dry_types.rb
index f0676c376d..5f1bc3cde9 100644
--- a/lib/grape/dry_types.rb
+++ b/lib/grape/dry_types.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'dry-types'
-
 module Grape
   module DryTypes
     # Call +Dry.Types()+ to add all registered types to +DryTypes+ which is
diff --git a/lib/grape/dsl/inside_route.rb b/lib/grape/dsl/inside_route.rb
index ef3bdec080..d93546061f 100644
--- a/lib/grape/dsl/inside_route.rb
+++ b/lib/grape/dsl/inside_route.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/dsl/headers'
-
 module Grape
   module DSL
     module InsideRoute
diff --git a/lib/grape/eager_load.rb b/lib/grape/eager_load.rb
deleted file mode 100644
index ef7bc3ec7c..0000000000
--- a/lib/grape/eager_load.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-# frozen_string_literal: true
-
-Grape.eager_load!
-Grape::Http.eager_load!
-Grape::Exceptions.eager_load!
-Grape::Extensions.eager_load!
-Grape::Extensions::ActiveSupport.eager_load!
-Grape::Extensions::Hashie.eager_load!
-Grape::Middleware.eager_load!
-Grape::Middleware::Auth.eager_load!
-Grape::Middleware::Versioner.eager_load!
-Grape::Util.eager_load!
-Grape::ErrorFormatter.eager_load!
-Grape::Formatter.eager_load!
-Grape::Parser.eager_load!
-Grape::DSL.eager_load!
-Grape::API.eager_load!
-Grape::Presenters.eager_load!
-Grape::ServeStream.eager_load!
-Rack::Head # AutoLoads the Rack::Head
diff --git a/lib/grape/util/env.rb b/lib/grape/env.rb
similarity index 100%
rename from lib/grape/util/env.rb
rename to lib/grape/env.rb
diff --git a/lib/grape/exceptions/validation.rb b/lib/grape/exceptions/validation.rb
index b66fc46c97..8d368d2776 100644
--- a/lib/grape/exceptions/validation.rb
+++ b/lib/grape/exceptions/validation.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/exceptions/base'
-
 module Grape
   module Exceptions
     class Validation < Grape::Exceptions::Base
diff --git a/lib/grape/exceptions/validation_errors.rb b/lib/grape/exceptions/validation_errors.rb
index 4b3d5b9e00..09e4a37b0a 100644
--- a/lib/grape/exceptions/validation_errors.rb
+++ b/lib/grape/exceptions/validation_errors.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/exceptions/base'
-
 module Grape
   module Exceptions
     class ValidationErrors < Grape::Exceptions::Base
diff --git a/lib/grape/http/headers.rb b/lib/grape/http/headers.rb
index a7e5984f75..ae0989a3b3 100644
--- a/lib/grape/http/headers.rb
+++ b/lib/grape/http/headers.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/util/lazy_object'
-
 module Grape
   module Http
     module Headers
@@ -11,7 +9,11 @@ module Headers
       REQUEST_METHOD  = 'REQUEST_METHOD'
       QUERY_STRING    = 'QUERY_STRING'
 
-      if Grape.lowercase_headers?
+      def self.lowercase?
+        Rack::CONTENT_TYPE == 'content-type'
+      end
+
+      if lowercase?
         ALLOW             = 'allow'
         LOCATION          = 'location'
         TRANSFER_ENCODING = 'transfer-encoding'
@@ -32,7 +34,7 @@ module Headers
       OPTIONS = 'OPTIONS'
 
       SUPPORTED_METHODS = [GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS].freeze
-      SUPPORTED_METHODS_WITHOUT_OPTIONS = Grape::Util::LazyObject.new { [GET, POST, PUT, PATCH, DELETE, HEAD].freeze }
+      SUPPORTED_METHODS_WITHOUT_OPTIONS = Grape::Util::Lazy::Object.new { [GET, POST, PUT, PATCH, DELETE, HEAD].freeze }
 
       HTTP_ACCEPT_VERSION    = 'HTTP_ACCEPT_VERSION'
       HTTP_TRANSFER_ENCODING = 'HTTP_TRANSFER_ENCODING'
@@ -40,7 +42,7 @@ module Headers
 
       FORMAT                 = 'format'
 
-      HTTP_HEADERS = Grape::Util::LazyObject.new do
+      HTTP_HEADERS = Grape::Util::Lazy::Object.new do
         common_http_headers = %w[
           Version
           Host
diff --git a/lib/grape/util/json.rb b/lib/grape/json.rb
similarity index 72%
rename from lib/grape/util/json.rb
rename to lib/grape/json.rb
index 26695e92ac..a30014538f 100644
--- a/lib/grape/util/json.rb
+++ b/lib/grape/json.rb
@@ -1,9 +1,7 @@
 # frozen_string_literal: true
 
-require 'json'
-
 module Grape
-  if Object.const_defined? :MultiJson
+  if defined?(::MultiJson)
     Json = ::MultiJson
   else
     Json = ::JSON
diff --git a/lib/grape/middleware/auth/base.rb b/lib/grape/middleware/auth/base.rb
index 67a1a53bbf..d7703cd783 100644
--- a/lib/grape/middleware/auth/base.rb
+++ b/lib/grape/middleware/auth/base.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'rack/auth/basic'
-
 module Grape
   module Middleware
     module Auth
diff --git a/lib/grape/middleware/auth/dsl.rb b/lib/grape/middleware/auth/dsl.rb
index eb27588b7d..598358d9d6 100644
--- a/lib/grape/middleware/auth/dsl.rb
+++ b/lib/grape/middleware/auth/dsl.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'rack/auth/basic'
-
 module Grape
   module Middleware
     module Auth
diff --git a/lib/grape/middleware/base.rb b/lib/grape/middleware/base.rb
index 5eb998fc08..87f2429fff 100644
--- a/lib/grape/middleware/base.rb
+++ b/lib/grape/middleware/base.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/dsl/headers'
-
 module Grape
   module Middleware
     class Base
diff --git a/lib/grape/middleware/error.rb b/lib/grape/middleware/error.rb
index 545519a1a1..dedb4cd586 100644
--- a/lib/grape/middleware/error.rb
+++ b/lib/grape/middleware/error.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/middleware/base'
-
 module Grape
   module Middleware
     class Error < Base
diff --git a/lib/grape/middleware/formatter.rb b/lib/grape/middleware/formatter.rb
index 0e87373d0b..2f0f7f0dfa 100644
--- a/lib/grape/middleware/formatter.rb
+++ b/lib/grape/middleware/formatter.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/middleware/base'
-
 module Grape
   module Middleware
     class Formatter < Base
diff --git a/lib/grape/middleware/globals.rb b/lib/grape/middleware/globals.rb
index 850f241967..10d5029dcc 100644
--- a/lib/grape/middleware/globals.rb
+++ b/lib/grape/middleware/globals.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/middleware/base'
-
 module Grape
   module Middleware
     class Globals < Base
diff --git a/lib/grape/middleware/versioner/accept_version_header.rb b/lib/grape/middleware/versioner/accept_version_header.rb
index 6198ae0cfa..98237e9476 100644
--- a/lib/grape/middleware/versioner/accept_version_header.rb
+++ b/lib/grape/middleware/versioner/accept_version_header.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/middleware/base'
-
 module Grape
   module Middleware
     module Versioner
diff --git a/lib/grape/middleware/versioner/header.rb b/lib/grape/middleware/versioner/header.rb
index f8c9f28230..33ea25660b 100644
--- a/lib/grape/middleware/versioner/header.rb
+++ b/lib/grape/middleware/versioner/header.rb
@@ -1,9 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/middleware/base'
-require 'grape/util/media_type'
-require 'grape/util/accept_header_handler'
-
 module Grape
   module Middleware
     module Versioner
@@ -37,11 +33,13 @@ def before
             content_types: content_types,
             allowed_methods: env[Grape::Env::GRAPE_ALLOWED_METHODS]
           ) do |media_type|
-            env[Grape::Env::API_TYPE] = media_type.type
-            env[Grape::Env::API_SUBTYPE] = media_type.subtype
-            env[Grape::Env::API_VENDOR] = media_type.vendor
-            env[Grape::Env::API_VERSION] = media_type.version
-            env[Grape::Env::API_FORMAT] = media_type.format
+            env.update(
+              Grape::Env::API_TYPE => media_type.type,
+              Grape::Env::API_SUBTYPE => media_type.subtype,
+              Grape::Env::API_VENDOR => media_type.vendor,
+              Grape::Env::API_VERSION => media_type.version,
+              Grape::Env::API_FORMAT => media_type.format
+            )
           end
         end
       end
diff --git a/lib/grape/middleware/versioner/param.rb b/lib/grape/middleware/versioner/param.rb
index 8e9fe36c0f..69b1d0f48f 100644
--- a/lib/grape/middleware/versioner/param.rb
+++ b/lib/grape/middleware/versioner/param.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/middleware/base'
-
 module Grape
   module Middleware
     module Versioner
diff --git a/lib/grape/middleware/versioner/path.rb b/lib/grape/middleware/versioner/path.rb
index ec15a6d7cf..d6c3e90dda 100644
--- a/lib/grape/middleware/versioner/path.rb
+++ b/lib/grape/middleware/versioner/path.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/middleware/base'
-
 module Grape
   module Middleware
     module Versioner
diff --git a/lib/grape/namespace.rb b/lib/grape/namespace.rb
index 3473d3efb1..8375e3a561 100644
--- a/lib/grape/namespace.rb
+++ b/lib/grape/namespace.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/util/cache'
-
 module Grape
   # A container for endpoints or other namespaces, which allows for both
   # logical grouping of endpoints as well as sharing common configuration.
diff --git a/lib/grape/path.rb b/lib/grape/path.rb
index e08725e52e..e6fa540e7e 100644
--- a/lib/grape/path.rb
+++ b/lib/grape/path.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/util/cache'
-
 module Grape
   # Represents a path to an endpoint.
   class Path
diff --git a/lib/grape/request.rb b/lib/grape/request.rb
index c907f0b4ab..8b75da98ea 100644
--- a/lib/grape/request.rb
+++ b/lib/grape/request.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/util/lazy_object'
-
 module Grape
   class Request < Rack::Request
     HTTP_PREFIX = 'HTTP_'
@@ -36,7 +34,7 @@ def grape_routing_args
     end
 
     def build_headers
-      Grape::Util::LazyObject.new do
+      Grape::Util::Lazy::Object.new do
         env.each_pair.with_object({}) do |(k, v), headers|
           next unless k.to_s.start_with? HTTP_PREFIX
 
@@ -46,7 +44,7 @@ def build_headers
       end
     end
 
-    if Grape.lowercase_headers?
+    if Grape::Http::Headers.lowercase?
       def transform_header(header)
         -header[5..].tr('_', '-').downcase
       end
diff --git a/lib/grape/router.rb b/lib/grape/router.rb
index 51107efbab..7d9dd85641 100644
--- a/lib/grape/router.rb
+++ b/lib/grape/router.rb
@@ -1,9 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/router/route'
-require 'grape/router/greedy_route'
-require 'grape/util/cache'
-
 module Grape
   class Router
     attr_reader :map, :compiled
diff --git a/lib/grape/router/greedy_route.rb b/lib/grape/router/greedy_route.rb
index 765aa83de9..787c1265b6 100644
--- a/lib/grape/router/greedy_route.rb
+++ b/lib/grape/router/greedy_route.rb
@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/router/attribute_translator'
-require 'forwardable'
-
 # Act like a Grape::Router::Route but for greedy_match
 # see @neutral_map
 
diff --git a/lib/grape/router/pattern.rb b/lib/grape/router/pattern.rb
index a1fce07a0b..0f646bea90 100644
--- a/lib/grape/router/pattern.rb
+++ b/lib/grape/router/pattern.rb
@@ -1,9 +1,5 @@
 # frozen_string_literal: true
 
-require 'forwardable'
-require 'mustermann/grape'
-require 'grape/util/cache'
-
 module Grape
   class Router
     class Pattern
diff --git a/lib/grape/router/route.rb b/lib/grape/router/route.rb
index 7d4a912a3b..2ee3bb89fb 100644
--- a/lib/grape/router/route.rb
+++ b/lib/grape/router/route.rb
@@ -1,9 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/router/pattern'
-require 'grape/router/attribute_translator'
-require 'forwardable'
-
 module Grape
   class Router
     class Route
diff --git a/lib/grape/util/accept/header.rb b/lib/grape/util/accept/header.rb
new file mode 100644
index 0000000000..3f6b3a67a9
--- /dev/null
+++ b/lib/grape/util/accept/header.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module Grape
+  module Util
+    module Accept
+      module Header
+        ALLOWED_CHARACTERS = %r{^([a-z*]+)/([a-z0-9*&\^\-_#{$ERROR_INFO}.+]+)(?:;([a-z0-9=;]+))?$}.freeze
+        class << self
+          # Corrected version of https://github.com/mjackson/rack-accept/blob/master/lib/rack/accept/header.rb#L40-L44
+          def parse_media_type(media_type)
+            # see http://tools.ietf.org/html/rfc6838#section-4.2 for allowed characters in media type names
+            m = media_type&.match(ALLOWED_CHARACTERS)
+            m ? [m[1], m[2], m[3] || ''] : []
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/grape/util/accept_header_handler.rb b/lib/grape/util/accept_header_handler.rb
index 25d7036319..c7fc7bee9a 100644
--- a/lib/grape/util/accept_header_handler.rb
+++ b/lib/grape/util/accept_header_handler.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/util/media_type'
-
 module Grape
   module Util
     class AcceptHeaderHandler
diff --git a/lib/grape/util/cache.rb b/lib/grape/util/cache.rb
index b58f432400..7514296c2b 100644
--- a/lib/grape/util/cache.rb
+++ b/lib/grape/util/cache.rb
@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require 'singleton'
-require 'forwardable'
-
 module Grape
   module Util
     class Cache
diff --git a/lib/grape/util/endpoint_configuration.rb b/lib/grape/util/endpoint_configuration.rb
index 90ad256f88..4985562551 100644
--- a/lib/grape/util/endpoint_configuration.rb
+++ b/lib/grape/util/endpoint_configuration.rb
@@ -2,7 +2,7 @@
 
 module Grape
   module Util
-    class EndpointConfiguration < LazyValueHash
+    class EndpointConfiguration < Lazy::ValueHash
     end
   end
 end
diff --git a/lib/grape/util/inheritable_values.rb b/lib/grape/util/inheritable_values.rb
index 6b43f8ca2b..48cebb23aa 100644
--- a/lib/grape/util/inheritable_values.rb
+++ b/lib/grape/util/inheritable_values.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative 'base_inheritable'
-
 module Grape
   module Util
     class InheritableValues < BaseInheritable
diff --git a/lib/grape/util/lazy/block.rb b/lib/grape/util/lazy/block.rb
new file mode 100644
index 0000000000..a47d44b094
--- /dev/null
+++ b/lib/grape/util/lazy/block.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module Grape
+  module Util
+    module Lazy
+      class Block
+        def initialize(&new_block)
+          @block = new_block
+        end
+
+        def evaluate_from(configuration)
+          @block.call(configuration)
+        end
+
+        def evaluate
+          @block.call({})
+        end
+
+        def lazy?
+          true
+        end
+
+        def to_s
+          evaluate.to_s
+        end
+      end
+    end
+  end
+end
diff --git a/lib/grape/util/lazy/object.rb b/lib/grape/util/lazy/object.rb
new file mode 100644
index 0000000000..6c10dadfcc
--- /dev/null
+++ b/lib/grape/util/lazy/object.rb
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+# Based on https://github.com/HornsAndHooves/lazy_object
+
+module Grape
+  module Util
+    module Lazy
+      class Object < BasicObject
+        attr_reader :callable
+
+        def initialize(&callable)
+          @callable = callable
+        end
+
+        def __target_object__
+          @__target_object__ ||= callable.call
+        end
+
+        def ==(other)
+          __target_object__ == other
+        end
+
+        def !=(other)
+          __target_object__ != other
+        end
+
+        def !
+          !__target_object__
+        end
+
+        def method_missing(method_name, *args, &block)
+          if __target_object__.respond_to?(method_name)
+            __target_object__.send(method_name, *args, &block)
+          else
+            super
+          end
+        end
+
+        def respond_to_missing?(method_name, include_priv = false)
+          __target_object__.respond_to?(method_name, include_priv)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/grape/util/lazy/value.rb b/lib/grape/util/lazy/value.rb
new file mode 100644
index 0000000000..59b7999470
--- /dev/null
+++ b/lib/grape/util/lazy/value.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+module Grape
+  module Util
+    module Lazy
+      class Value
+        attr_reader :access_keys
+
+        def initialize(value, access_keys = [])
+          @value = value
+          @access_keys = access_keys
+        end
+
+        def evaluate_from(configuration)
+          matching_lazy_value = configuration.fetch(@access_keys)
+          matching_lazy_value.evaluate
+        end
+
+        def evaluate
+          @value
+        end
+
+        def lazy?
+          true
+        end
+
+        def reached_by(parent_access_keys, access_key)
+          @access_keys = parent_access_keys + [access_key]
+          self
+        end
+
+        def to_s
+          evaluate.to_s
+        end
+      end
+    end
+  end
+end
diff --git a/lib/grape/util/lazy/value_array.rb b/lib/grape/util/lazy/value_array.rb
new file mode 100644
index 0000000000..b4c6a88ab1
--- /dev/null
+++ b/lib/grape/util/lazy/value_array.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module Grape
+  module Util
+    module Lazy
+      class ValueArray < ValueEnumerable
+        def initialize(array)
+          super
+          @value_hash = []
+          array.each_with_index do |value, index|
+            self[index] = value
+          end
+        end
+
+        def evaluate
+          @value_hash.map(&:evaluate)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/grape/util/lazy/value_enumerable.rb b/lib/grape/util/lazy/value_enumerable.rb
new file mode 100644
index 0000000000..ce15693aac
--- /dev/null
+++ b/lib/grape/util/lazy/value_enumerable.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module Grape
+  module Util
+    module Lazy
+      class ValueEnumerable < Value
+        def [](key)
+          if @value_hash[key].nil?
+            Value.new(nil).reached_by(access_keys, key)
+          else
+            @value_hash[key].reached_by(access_keys, key)
+          end
+        end
+
+        def fetch(access_keys)
+          fetched_keys = access_keys.dup
+          value = self[fetched_keys.shift]
+          fetched_keys.any? ? value.fetch(fetched_keys) : value
+        end
+
+        def []=(key, value)
+          @value_hash[key] = case value
+                             when Hash
+                               ValueHash.new(value)
+                             when Array
+                               ValueArray.new(value)
+                             else
+                               Value.new(value)
+                             end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/grape/util/lazy/value_hash.rb b/lib/grape/util/lazy/value_hash.rb
new file mode 100644
index 0000000000..c3447a0ddc
--- /dev/null
+++ b/lib/grape/util/lazy/value_hash.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module Grape
+  module Util
+    module Lazy
+      class ValueHash < ValueEnumerable
+        def initialize(hash)
+          super
+          @value_hash = ActiveSupport::HashWithIndifferentAccess.new
+          hash.each do |key, value|
+            self[key] = value
+          end
+        end
+
+        def evaluate
+          @value_hash.transform_values(&:evaluate)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/grape/util/lazy_block.rb b/lib/grape/util/lazy_block.rb
deleted file mode 100644
index 6e7d18b8a1..0000000000
--- a/lib/grape/util/lazy_block.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-# frozen_string_literal: true
-
-module Grape
-  module Util
-    class LazyBlock
-      def initialize(&new_block)
-        @block = new_block
-      end
-
-      def evaluate_from(configuration)
-        @block.call(configuration)
-      end
-
-      def evaluate
-        @block.call({})
-      end
-
-      def lazy?
-        true
-      end
-
-      def to_s
-        evaluate.to_s
-      end
-    end
-  end
-end
diff --git a/lib/grape/util/lazy_object.rb b/lib/grape/util/lazy_object.rb
deleted file mode 100644
index 22ec7c440d..0000000000
--- a/lib/grape/util/lazy_object.rb
+++ /dev/null
@@ -1,43 +0,0 @@
-# frozen_string_literal: true
-
-# Based on https://github.com/HornsAndHooves/lazy_object
-
-module Grape
-  module Util
-    class LazyObject < BasicObject
-      attr_reader :callable
-
-      def initialize(&callable)
-        @callable = callable
-      end
-
-      def __target_object__
-        @__target_object__ ||= callable.call
-      end
-
-      def ==(other)
-        __target_object__ == other
-      end
-
-      def !=(other)
-        __target_object__ != other
-      end
-
-      def !
-        !__target_object__
-      end
-
-      def method_missing(method_name, *args, &block)
-        if __target_object__.respond_to?(method_name)
-          __target_object__.send(method_name, *args, &block)
-        else
-          super
-        end
-      end
-
-      def respond_to_missing?(method_name, include_priv = false)
-        __target_object__.respond_to?(method_name, include_priv)
-      end
-    end
-  end
-end
diff --git a/lib/grape/util/lazy_value.rb b/lib/grape/util/lazy_value.rb
deleted file mode 100644
index cc732562f9..0000000000
--- a/lib/grape/util/lazy_value.rb
+++ /dev/null
@@ -1,91 +0,0 @@
-# frozen_string_literal: true
-
-module Grape
-  module Util
-    class LazyValue
-      attr_reader :access_keys
-
-      def initialize(value, access_keys = [])
-        @value = value
-        @access_keys = access_keys
-      end
-
-      def evaluate_from(configuration)
-        matching_lazy_value = configuration.fetch(@access_keys)
-        matching_lazy_value.evaluate
-      end
-
-      def evaluate
-        @value
-      end
-
-      def lazy?
-        true
-      end
-
-      def reached_by(parent_access_keys, access_key)
-        @access_keys = parent_access_keys + [access_key]
-        self
-      end
-
-      def to_s
-        evaluate.to_s
-      end
-    end
-
-    class LazyValueEnumerable < LazyValue
-      def [](key)
-        if @value_hash[key].nil?
-          LazyValue.new(nil).reached_by(access_keys, key)
-        else
-          @value_hash[key].reached_by(access_keys, key)
-        end
-      end
-
-      def fetch(access_keys)
-        fetched_keys = access_keys.dup
-        value = self[fetched_keys.shift]
-        fetched_keys.any? ? value.fetch(fetched_keys) : value
-      end
-
-      def []=(key, value)
-        @value_hash[key] = case value
-                           when Hash
-                             LazyValueHash.new(value)
-                           when Array
-                             LazyValueArray.new(value)
-                           else
-                             LazyValue.new(value)
-                           end
-      end
-    end
-
-    class LazyValueArray < LazyValueEnumerable
-      def initialize(array)
-        super
-        @value_hash = []
-        array.each_with_index do |value, index|
-          self[index] = value
-        end
-      end
-
-      def evaluate
-        @value_hash.map(&:evaluate)
-      end
-    end
-
-    class LazyValueHash < LazyValueEnumerable
-      def initialize(hash)
-        super
-        @value_hash = ActiveSupport::HashWithIndifferentAccess.new
-        hash.each do |key, value|
-          self[key] = value
-        end
-      end
-
-      def evaluate
-        @value_hash.transform_values(&:evaluate)
-      end
-    end
-  end
-end
diff --git a/lib/grape/util/reverse_stackable_values.rb b/lib/grape/util/reverse_stackable_values.rb
index 171f390f73..3b008a926c 100644
--- a/lib/grape/util/reverse_stackable_values.rb
+++ b/lib/grape/util/reverse_stackable_values.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative 'stackable_values'
-
 module Grape
   module Util
     class ReverseStackableValues < StackableValues
diff --git a/lib/grape/util/stackable_values.rb b/lib/grape/util/stackable_values.rb
index 01a5681965..c19e2f5828 100644
--- a/lib/grape/util/stackable_values.rb
+++ b/lib/grape/util/stackable_values.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative 'base_inheritable'
-
 module Grape
   module Util
     class StackableValues < BaseInheritable
diff --git a/lib/grape/validations.rb b/lib/grape/validations.rb
index 74d534f377..9ae22ae6a1 100644
--- a/lib/grape/validations.rb
+++ b/lib/grape/validations.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 module Grape
-  # Registry to store and locate known Validators.
   module Validations
     module_function
 
@@ -12,7 +11,7 @@ def validators
     # Register a new validator, so it can be used to validate parameters.
     # @param short_name [String] all lower-case, no spaces
     # @param klass [Class] the validator class. Should inherit from
-    #   Validations::Base.
+    #   Grape::Validations::Validators::Base.
     def register_validator(short_name, klass)
       validators[short_name] = klass
     end
@@ -21,14 +20,11 @@ def deregister_validator(short_name)
       validators.delete(short_name)
     end
 
-    # Find a validator and if not found will try to load it
     def require_validator(short_name)
       str_name = short_name.to_s
-      validators.fetch(str_name) do
-        Grape::Validations::Validators.const_get(:"#{str_name.camelize}Validator")
-      end
+      validators.fetch(str_name) { Grape::Validations::Validators.const_get(:"#{str_name.camelize}Validator") }
     rescue NameError
-      raise Grape::Exceptions::UnknownValidator.new(short_name)
+      raise Grape::Exceptions::UnknownValidator, short_name
     end
   end
 end
diff --git a/lib/grape/validations/attributes_doc.rb b/lib/grape/validations/attributes_doc.rb
index a046707039..f9e15c148a 100644
--- a/lib/grape/validations/attributes_doc.rb
+++ b/lib/grape/validations/attributes_doc.rb
@@ -2,56 +2,55 @@
 
 module Grape
   module Validations
-    class ParamsScope
-      # Documents parameters of an endpoint. If documentation isn't needed (for instance, it is an
-      # internal API), the class only cleans up attributes to avoid junk in RAM.
-      class AttributesDoc
-        attr_accessor :type, :values
-
-        # @param api [Grape::API::Instance]
-        # @param scope [Validations::ParamsScope]
-        def initialize(api, scope)
-          @api = api
-          @scope = scope
-          @type = type
-        end
+    # Documents parameters of an endpoint. If documentation isn't needed (for instance, it is an
+    # internal API), the class only cleans up attributes to avoid junk in RAM.
+
+    class AttributesDoc
+      attr_accessor :type, :values
+
+      # @param api [Grape::API::Instance]
+      # @param scope [Validations::ParamsScope]
+      def initialize(api, scope)
+        @api = api
+        @scope = scope
+        @type = type
+      end
 
-        def extract_details(validations)
-          details[:required] = validations.key?(:presence)
+      def extract_details(validations)
+        details[:required] = validations.key?(:presence)
 
-          desc = validations.delete(:desc) || validations.delete(:description)
+        desc = validations.delete(:desc) || validations.delete(:description)
 
-          details[:desc] = desc if desc
+        details[:desc] = desc if desc
 
-          documentation = validations.delete(:documentation)
+        documentation = validations.delete(:documentation)
 
-          details[:documentation] = documentation if documentation
+        details[:documentation] = documentation if documentation
 
-          details[:default] = validations[:default] if validations.key?(:default)
-        end
-
-        def document(attrs)
-          return if @api.namespace_inheritable(:do_not_document)
+        details[:default] = validations[:default] if validations.key?(:default)
+      end
 
-          details[:type] = type.to_s if type
-          details[:values] = values if values
+      def document(attrs)
+        return if @api.namespace_inheritable(:do_not_document)
 
-          documented_attrs = attrs.each_with_object({}) do |name, memo|
-            memo[@scope.full_name(name)] = details
-          end
+        details[:type] = type.to_s if type
+        details[:values] = values if values
 
-          @api.namespace_stackable(:params, documented_attrs)
+        documented_attrs = attrs.each_with_object({}) do |name, memo|
+          memo[@scope.full_name(name)] = details
         end
 
-        def required
-          details[:required]
-        end
+        @api.namespace_stackable(:params, documented_attrs)
+      end
 
-        protected
+      def required
+        details[:required]
+      end
 
-        def details
-          @details ||= {}
-        end
+      protected
+
+      def details
+        @details ||= {}
       end
     end
   end
diff --git a/lib/grape/validations/params_scope.rb b/lib/grape/validations/params_scope.rb
index 6eaf7abaa4..026e7df9ce 100644
--- a/lib/grape/validations/params_scope.rb
+++ b/lib/grape/validations/params_scope.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative 'attributes_doc'
-
 module Grape
   module Validations
     class ParamsScope
diff --git a/lib/grape/validations/types.rb b/lib/grape/validations/types.rb
index 1e45c4f7fe..86f9c9b601 100644
--- a/lib/grape/validations/types.rb
+++ b/lib/grape/validations/types.rb
@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/validations/types/json'
-require 'grape/validations/types/file'
-
 module Grape
   module Validations
     # Module for code related to grape's system for
diff --git a/lib/grape/validations/types/array_coercer.rb b/lib/grape/validations/types/array_coercer.rb
index c6d6b106e1..ec4ca41dee 100644
--- a/lib/grape/validations/types/array_coercer.rb
+++ b/lib/grape/validations/types/array_coercer.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative 'dry_type_coercer'
-
 module Grape
   module Validations
     module Types
diff --git a/lib/grape/validations/types/build_coercer.rb b/lib/grape/validations/types/build_coercer.rb
index c55e048dbd..5f15a1a0cb 100644
--- a/lib/grape/validations/types/build_coercer.rb
+++ b/lib/grape/validations/types/build_coercer.rb
@@ -1,94 +1,92 @@
 # frozen_string_literal: true
 
-require_relative 'array_coercer'
-require_relative 'set_coercer'
-require_relative 'primitive_coercer'
-
 module Grape
   module Validations
     module Types
-      # Chooses the best coercer for the given type. For example, if the type
-      # is Integer, it will return a coercer which will be able to coerce a value
-      # to the integer.
-      #
-      # There are a few very special coercers which might be returned.
-      #
-      # +Grape::Types::MultipleTypeCoercer+ is a coercer which is returned when
-      # the given type implies values in an array with different types.
-      # For example, +[Integer, String]+ allows integer and string values in
-      # an array.
-      #
-      # +Grape::Types::CustomTypeCoercer+ is a coercer which is returned when
-      # a method is specified by a user with +coerce_with+ option or the user
-      # specifies a custom type which implements requirments of
-      # +Grape::Types::CustomTypeCoercer+.
-      #
-      # +Grape::Types::CustomTypeCollectionCoercer+ is a very similar to the
-      # previous one, but it expects an array or set of values having a custom
-      # type implemented by the user.
-      #
-      # There is also a group of custom types implemented by Grape, check
-      # +Grape::Validations::Types::SPECIAL+ to get the full list.
-      #
-      # @param type [Class] the type to which input strings
-      #   should be coerced
-      # @param method [Class,#call] the coercion method to use
-      # @return [Object] object to be used
-      #   for coercion and type validation
-      def self.build_coercer(type, method: nil, strict: false)
-        cache_instance(type, method, strict) do
-          create_coercer_instance(type, method, strict)
+      module BuildCoercer
+        # Chooses the best coercer for the given type. For example, if the type
+        # is Integer, it will return a coercer which will be able to coerce a value
+        # to the integer.
+        #
+        # There are a few very special coercers which might be returned.
+        #
+        # +Grape::Types::MultipleTypeCoercer+ is a coercer which is returned when
+        # the given type implies values in an array with different types.
+        # For example, +[Integer, String]+ allows integer and string values in
+        # an array.
+        #
+        # +Grape::Types::CustomTypeCoercer+ is a coercer which is returned when
+        # a method is specified by a user with +coerce_with+ option or the user
+        # specifies a custom type which implements requirments of
+        # +Grape::Types::CustomTypeCoercer+.
+        #
+        # +Grape::Types::CustomTypeCollectionCoercer+ is a very similar to the
+        # previous one, but it expects an array or set of values having a custom
+        # type implemented by the user.
+        #
+        # There is also a group of custom types implemented by Grape, check
+        # +Grape::Validations::Types::SPECIAL+ to get the full list.
+        #
+        # @param type [Class] the type to which input strings
+        #   should be coerced
+        # @param method [Class,#call] the coercion method to use
+        # @return [Object] object to be used
+        #   for coercion and type validation
+        def self.build_coercer(type, method: nil, strict: false)
+          cache_instance(type, method, strict) do
+            create_coercer_instance(type, method, strict)
+          end
         end
-      end
 
-      def self.create_coercer_instance(type, method, strict)
-        # Maps a custom type provided by Grape, it doesn't map types wrapped by collections!!!
-        type = Types.map_special(type)
+        def self.create_coercer_instance(type, method, strict)
+          # Maps a custom type provided by Grape, it doesn't map types wrapped by collections!!!
+          type = Types.map_special(type)
 
-        # Use a special coercer for multiply-typed parameters.
-        if Types.multiple?(type)
-          MultipleTypeCoercer.new(type, method)
+          # Use a special coercer for multiply-typed parameters.
+          if Types.multiple?(type)
+            MultipleTypeCoercer.new(type, method)
 
-        # Use a special coercer for custom types and coercion methods.
-        elsif method || Types.custom?(type)
-          CustomTypeCoercer.new(type, method)
+            # Use a special coercer for custom types and coercion methods.
+          elsif method || Types.custom?(type)
+            CustomTypeCoercer.new(type, method)
 
-        # Special coercer for collections of types that implement a parse method.
-        # CustomTypeCoercer (above) already handles such types when an explicit coercion
-        # method is supplied.
-        elsif Types.collection_of_custom?(type)
-          Types::CustomTypeCollectionCoercer.new(
-            Types.map_special(type.first), type.is_a?(Set)
-          )
-        else
-          DryTypeCoercer.coercer_instance_for(type, strict)
+            # Special coercer for collections of types that implement a parse method.
+            # CustomTypeCoercer (above) already handles such types when an explicit coercion
+            # method is supplied.
+          elsif Types.collection_of_custom?(type)
+            Types::CustomTypeCollectionCoercer.new(
+              Types.map_special(type.first), type.is_a?(Set)
+            )
+          else
+            DryTypeCoercer.coercer_instance_for(type, strict)
+          end
         end
-      end
 
-      def self.cache_instance(type, method, strict, &_block)
-        key = cache_key(type, method, strict)
+        def self.cache_instance(type, method, strict, &_block)
+          key = cache_key(type, method, strict)
 
-        return @__cache[key] if @__cache.key?(key)
+          return @__cache[key] if @__cache.key?(key)
 
-        instance = yield
+          instance = yield
 
-        @__cache_write_lock.synchronize do
-          @__cache[key] = instance
-        end
+          @__cache_write_lock.synchronize do
+            @__cache[key] = instance
+          end
 
-        instance
-      end
+          instance
+        end
 
-      def self.cache_key(type, method, strict)
-        [type, method, strict].each_with_object(+'_') do |val, memo|
-          next if val.nil?
+        def self.cache_key(type, method, strict)
+          [type, method, strict].each_with_object(+'_') do |val, memo|
+            next if val.nil?
 
-          memo << '_' << val.to_s
+            memo << '_' << val.to_s
+          end
         end
-      end
 
-      instance_variable_set(:@__cache,            {})
-      instance_variable_set(:@__cache_write_lock, Mutex.new)
+        instance_variable_set(:@__cache,            {})
+        instance_variable_set(:@__cache_write_lock, Mutex.new)
+      end
     end
   end
 end
diff --git a/lib/grape/validations/types/dry_type_coercer.rb b/lib/grape/validations/types/dry_type_coercer.rb
index cc529c07c8..1067eaf3a8 100644
--- a/lib/grape/validations/types/dry_type_coercer.rb
+++ b/lib/grape/validations/types/dry_type_coercer.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'dry-types'
-
 module DryTypes
   # Call +Dry.Types()+ to add all registered types to +DryTypes+ which is
   # a container in this case. Check documentation for more information
@@ -24,9 +22,7 @@ class << self
           #    collection_coercer_for(Array)
           #    #=> Grape::Validations::Types::ArrayCoercer
           def collection_coercer_for(type)
-            collection_coercers.fetch(type) do
-              DryTypeCoercer.collection_coercers[type] = Grape::Validations::Types.const_get(:"#{type.name.camelize}Coercer")
-            end
+            Grape::Validations::Types.const_get(:"#{type.name.camelize}Coercer")
           end
 
           # Returns an instance of a coercer for a given type
@@ -37,12 +33,6 @@ def coercer_instance_for(type, strict = false)
             # so we need to figure out the actual type
             collection_coercer_for(type.class).new(type, strict)
           end
-
-          protected
-
-          def collection_coercers
-            @collection_coercers ||= {}
-          end
         end
 
         def initialize(type, strict = false)
diff --git a/lib/grape/validations/types/json.rb b/lib/grape/validations/types/json.rb
index 3240de27b6..61b01131ce 100644
--- a/lib/grape/validations/types/json.rb
+++ b/lib/grape/validations/types/json.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'json'
-
 module Grape
   module Validations
     module Types
diff --git a/lib/grape/validations/types/primitive_coercer.rb b/lib/grape/validations/types/primitive_coercer.rb
index e2e3f9df54..e59b5c6eb8 100644
--- a/lib/grape/validations/types/primitive_coercer.rb
+++ b/lib/grape/validations/types/primitive_coercer.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative 'dry_type_coercer'
-
 module Grape
   module Validations
     module Types
diff --git a/lib/grape/validations/types/set_coercer.rb b/lib/grape/validations/types/set_coercer.rb
index 2d385c935d..9b1b311f8c 100644
--- a/lib/grape/validations/types/set_coercer.rb
+++ b/lib/grape/validations/types/set_coercer.rb
@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require 'set'
-require_relative 'array_coercer'
-
 module Grape
   module Validations
     module Types
diff --git a/lib/grape/validations/validators/base.rb b/lib/grape/validations/validators/base.rb
index c76eb4b394..3dd49fd797 100644
--- a/lib/grape/validations/validators/base.rb
+++ b/lib/grape/validations/validators/base.rb
@@ -59,6 +59,7 @@ def validate!(params)
         end
 
         def self.inherited(klass)
+          super
           return if klass.name.blank?
 
           short_validator_name = klass.name.demodulize.underscore.delete_suffix('_validator')
diff --git a/lib/grape/util/xml.rb b/lib/grape/xml.rb
similarity index 80%
rename from lib/grape/util/xml.rb
rename to lib/grape/xml.rb
index d948f8012f..85287814a3 100644
--- a/lib/grape/util/xml.rb
+++ b/lib/grape/xml.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module Grape
-  if Object.const_defined? :MultiXml
+  if defined?(::MultiXml)
     Xml = ::MultiXml
   else
     Xml = ::ActiveSupport::XmlMini
diff --git a/spec/grape/api/custom_validations_spec.rb b/spec/grape/api/custom_validations_spec.rb
index a6b7a629c1..49571a803e 100644
--- a/spec/grape/api/custom_validations_spec.rb
+++ b/spec/grape/api/custom_validations_spec.rb
@@ -35,13 +35,7 @@ def validate_param!(attr_name, params)
     end
     let(:app) { Rack::Builder.new(subject) }
 
-    before do
-      described_class.register_validator('default_length', default_length_validator)
-    end
-
-    after do
-      described_class.deregister_validator('default_length')
-    end
+    before { stub_const('Grape::Validations::Validators::DefaultLengthValidator', default_length_validator) }
 
     it 'under 140 characters' do
       get '/', text: 'abc'
@@ -83,13 +77,7 @@ def validate(request)
     end
     let(:app) { Rack::Builder.new(subject) }
 
-    before do
-      described_class.register_validator('in_body', in_body_validator)
-    end
-
-    after do
-      described_class.deregister_validator('in_body')
-    end
+    before { stub_const('Grape::Validations::Validators::InBodyValidator', in_body_validator) }
 
     it 'allows field in body' do
       get '/', text: 'abc'
@@ -125,13 +113,7 @@ def validate_param!(attr_name, _params)
     end
     let(:app) { Rack::Builder.new(subject) }
 
-    before do
-      described_class.register_validator('with_message_key', message_key_validator)
-    end
-
-    after do
-      described_class.deregister_validator('with_message_key')
-    end
+    before { stub_const('Grape::Validations::Validators::WithMessageKeyValidator', message_key_validator) }
 
     it 'fails with message' do
       get '/', text: 'foobar'
@@ -169,20 +151,15 @@ def validate(request)
         end
 
         def access_header
-          Grape.lowercase_headers? ? 'x-access-token' : 'X-Access-Token'
+          Grape::Http::Headers.lowercase? ? 'x-access-token' : 'X-Access-Token'
         end
       end
     end
+
     let(:app) { Rack::Builder.new(subject) }
-    let(:x_access_token_header) { Grape.lowercase_headers? ? 'x-access-token' : 'X-Access-Token' }
+    let(:x_access_token_header) { Grape::Http::Headers.lowercase? ? 'x-access-token' : 'X-Access-Token' }
 
-    before do
-      described_class.register_validator('admin', admin_validator)
-    end
-
-    after do
-      described_class.deregister_validator('admin')
-    end
+    before { stub_const('Grape::Validations::Validators::AdminValidator', admin_validator) }
 
     it 'fail when non-admin user sets an admin field' do
       get '/', admin_field: 'tester', non_admin_field: 'toaster'
@@ -216,4 +193,37 @@ def access_header
       expect(last_response.body).to include 'Can not set Admin only field.'
     end
   end
+
+  describe 'using a custom validator with instance variable' do
+    let(:validator_type) do
+      Class.new(Grape::Validations::Validators::Base) do
+        def validate_param!(_attr_name, _params)
+          if instance_variable_defined?(:@instance_variable) && @instance_variable
+            raise Grape::Exceptions::Validation.new(params: ['params'],
+                                                    message: 'This should never happen')
+          end
+          @instance_variable = true
+        end
+      end
+    end
+    let(:app) do
+      Class.new(Grape::API) do
+        params do
+          optional :param_to_validate, instance_validator: true
+          optional :another_param_to_validate, instance_validator: true
+        end
+        get do
+          'noop'
+        end
+      end
+    end
+
+    before { stub_const('Grape::Validations::Validators::InstanceValidatorValidator', validator_type) }
+
+    it 'passes validation every time' do
+      expect(validator_type).to receive(:new).twice.and_call_original
+      get '/', param_to_validate: 'value', another_param_to_validate: 'value'
+      expect(last_response.status).to eq 200
+    end
+  end
 end
diff --git a/spec/grape/api_spec.rb b/spec/grape/api_spec.rb
index f8bb785ff6..75f626f1a7 100644
--- a/spec/grape/api_spec.rb
+++ b/spec/grape/api_spec.rb
@@ -998,11 +998,6 @@ def to_txt
   end
 
   describe '.compile!' do
-    it 'requires the grape/eager_load file' do
-      expect(app).to receive(:require).with('grape/eager_load').and_return(nil)
-      app.compile!
-    end
-
     it 'compiles the instance for rack!' do
       stubbed_object = double(:instance_for_rack)
       allow(app).to receive(:instance_for_rack) { stubbed_object }
diff --git a/spec/grape/endpoint_spec.rb b/spec/grape/endpoint_spec.rb
index d8e88aeb10..c2443cbe7c 100644
--- a/spec/grape/endpoint_spec.rb
+++ b/spec/grape/endpoint_spec.rb
@@ -146,7 +146,7 @@ def app
 
     it 'includes additional request headers' do
       get '/headers', nil, 'HTTP_X_GRAPE_CLIENT' => '1'
-      x_grape_client_header = Grape.lowercase_headers? ? 'x-grape-client' : 'X-Grape-Client'
+      x_grape_client_header = Grape::Http::Headers.lowercase? ? 'x-grape-client' : 'X-Grape-Client'
       expect(JSON.parse(last_response.body)[x_grape_client_header]).to eq('1')
     end
 
@@ -154,7 +154,7 @@ def app
       env = Rack::MockRequest.env_for('/headers')
       env[:HTTP_SYMBOL_HEADER] = 'Goliath passes symbols'
       body = read_chunks(subject.call(env)[2]).join
-      symbol_header = Grape.lowercase_headers? ? 'symbol-header' : 'Symbol-Header'
+      symbol_header = Grape::Http::Headers.lowercase? ? 'symbol-header' : 'Symbol-Header'
       expect(JSON.parse(body)[symbol_header]).to eq('Goliath passes symbols')
     end
   end
diff --git a/spec/grape/request_spec.rb b/spec/grape/request_spec.rb
index b84b6dffdc..94d9f505a0 100644
--- a/spec/grape/request_spec.rb
+++ b/spec/grape/request_spec.rb
@@ -90,7 +90,7 @@ module Grape
           }
         end
         let(:x_grape_is_cool_header) do
-          Grape.lowercase_headers? ? 'x-grape-is-cool' : 'X-Grape-Is-Cool'
+          Grape::Http::Headers.lowercase? ? 'x-grape-is-cool' : 'X-Grape-Is-Cool'
         end
 
         it 'cuts HTTP_ prefix and capitalizes header name words' do
@@ -120,7 +120,7 @@ module Grape
           default_env.merge(request_headers)
         end
         let(:grape_likes_symbolic_header) do
-          Grape.lowercase_headers? ? 'grape-likes-symbolic' : 'Grape-Likes-Symbolic'
+          Grape::Http::Headers.lowercase? ? 'grape-likes-symbolic' : 'Grape-Likes-Symbolic'
         end
 
         it 'converts them to string' do
diff --git a/spec/grape/util/accept_header_handler_spec.rb b/spec/grape/util/accept_header_handler_spec.rb
index ac4ff3f461..de85ed26b5 100644
--- a/spec/grape/util/accept_header_handler_spec.rb
+++ b/spec/grape/util/accept_header_handler_spec.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'grape/util/accept_header_handler'
-
 RSpec.describe Grape::Util::AcceptHeaderHandler do
   subject(:match_best_quality_media_type!) { instance.match_best_quality_media_type! }
 
diff --git a/spec/grape/validations/attributes_doc_spec.rb b/spec/grape/validations/attributes_doc_spec.rb
index a21ce3591c..f1ae0c93e1 100644
--- a/spec/grape/validations/attributes_doc_spec.rb
+++ b/spec/grape/validations/attributes_doc_spec.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-describe Grape::Validations::ParamsScope::AttributesDoc do
+describe Grape::Validations::AttributesDoc do
   shared_examples 'an optional doc attribute' do |attr|
     it 'does not mention it' do
       expected_opts.delete(attr)
diff --git a/spec/grape/validations/instance_behaivour_spec.rb b/spec/grape/validations/instance_behaivour_spec.rb
deleted file mode 100644
index c8df967564..0000000000
--- a/spec/grape/validations/instance_behaivour_spec.rb
+++ /dev/null
@@ -1,43 +0,0 @@
-# frozen_string_literal: true
-
-describe 'Validator with instance variables' do
-  let(:validator_type) do
-    Class.new(Grape::Validations::Validators::Base) do
-      def validate_param!(_attr_name, _params)
-        if instance_variable_defined?(:@instance_variable) && @instance_variable
-          raise Grape::Exceptions::Validation.new(params: ['params'],
-                                                  message: 'This should never happen')
-        end
-        @instance_variable = true
-      end
-    end
-  end
-  let(:app) do
-    Class.new(Grape::API) do
-      params do
-        optional :param_to_validate, instance_validator: true
-        optional :another_param_to_validate, instance_validator: true
-      end
-      get do
-        'noop'
-      end
-    end
-  end
-
-  before do
-    Grape::Validations.register_validator('instance_validator', validator_type)
-  end
-
-  after do
-    Grape::Validations.deregister_validator('instance_validator')
-  end
-
-  it 'passes validation every time' do
-    expect(validator_type).to receive(:new).exactly(4).times.and_call_original
-
-    2.times do
-      get '/', param_to_validate: 'value', another_param_to_validate: 'value'
-      expect(last_response.status).to eq 200
-    end
-  end
-end
diff --git a/spec/grape/validations/validators/base_spec.rb b/spec/grape/validations/validators/base_spec.rb
deleted file mode 100644
index 9f1ff97601..0000000000
--- a/spec/grape/validations/validators/base_spec.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-# frozen_string_literal: true
-
-RSpec.describe Grape::Validations::Validators::Base do
-  describe '#inherited' do
-    context 'when validator is anonymous' do
-      subject(:custom_validator) { Class.new(described_class) }
-
-      it 'does not register the validator' do
-        expect(Grape::Validations).not_to receive(:register_validator)
-        custom_validator
-      end
-    end
-
-    # Anonymous class does not have a name and class A < B would leak.
-    # Simulates inherited callback
-    context "when validator's underscored name does not end with _validator" do
-      subject(:custom_validator) { described_class.inherited(TestModule::CustomValidatorABC) }
-
-      before { stub_const('TestModule::CustomValidatorABC', Class.new) }
-
-      it 'registers the custom validator with a short name' do
-        expect(Grape::Validations).to receive(:register_validator).with('custom_validator_abc', TestModule::CustomValidatorABC)
-        custom_validator
-      end
-    end
-
-    context "when validator's underscored name ends with _validator" do
-      subject(:custom_validator) { described_class.inherited(TestModule::CustomValidator) }
-
-      before { stub_const('TestModule::CustomValidator', Class.new) }
-
-      it 'registers the custom validator with short name not ending with validator' do
-        expect(Grape::Validations).to receive(:register_validator).with('custom', TestModule::CustomValidator)
-        custom_validator
-      end
-    end
-  end
-end
diff --git a/spec/grape/validations_spec.rb b/spec/grape/validations_spec.rb
index 58ab8a5792..12acb33d3c 100644
--- a/spec/grape/validations_spec.rb
+++ b/spec/grape/validations_spec.rb
@@ -3,9 +3,8 @@
 describe Grape::Validations do
   subject { Class.new(Grape::API) }
 
-  def app
-    subject
-  end
+  let(:app) { subject }
+  let(:declard_params) {}
 
   def declared_params
     subject.namespace_stackable(:declared_params).flatten
@@ -499,14 +498,7 @@ def validate_param!(attr_name, params)
       end
 
       before do
-        described_class.register_validator('date_range', date_range_validator)
-      end
-
-      after do
-        described_class.deregister_validator('date_range')
-      end
-
-      before do
+        stub_const('Grape::Validations::Validators::DateRangeValidator', date_range_validator)
         subject.params do
           optional :date_range, date_range: true, type: Hash do
             requires :from, type: Integer
@@ -1198,13 +1190,7 @@ def validate_param!(attr_name, params)
         end
       end
 
-      before do
-        described_class.register_validator('customvalidator', custom_validator)
-      end
-
-      after do
-        described_class.deregister_validator('customvalidator')
-      end
+      before { stub_const('Grape::Validations::Validators::CustomvalidatorValidator', custom_validator) }
 
       context 'when using optional with a custom validator' do
         before do
@@ -1356,14 +1342,8 @@ def validate_param!(attr_name, params)
         end
 
         before do
-          described_class.register_validator('customvalidator_with_options', custom_validator_with_options)
-        end
+          stub_const('Grape::Validations::Validators::CustomvalidatorWithOptionsValidator', custom_validator_with_options)
 
-        after do
-          described_class.deregister_validator('customvalidator_with_options')
-        end
-
-        before do
           subject.params do
             optional :custom, customvalidator_with_options: { text: 'im custom with options', message: 'is not custom with options!' }
           end
diff --git a/spec/integration/eager_load/eager_load_spec.rb b/spec/integration/eager_load/eager_load_spec.rb
deleted file mode 100644
index 174ba99440..0000000000
--- a/spec/integration/eager_load/eager_load_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-# frozen_string_literal: true
-
-$LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', '..', 'lib'))
-require 'grape'
-
-describe Grape do
-  it 'eager_load!' do
-    require 'grape/eager_load'
-    expect { described_class.eager_load! }.not_to raise_error
-  end
-
-  it 'compile!' do
-    expect { Class.new(Grape::API).compile! }.not_to raise_error
-  end
-end
diff --git a/spec/integration/multi_json/json_spec.rb b/spec/integration/multi_json/json_spec.rb
index 18ac22b724..a4227cdde6 100644
--- a/spec/integration/multi_json/json_spec.rb
+++ b/spec/integration/multi_json/json_spec.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-describe Grape::Json do
+describe Grape::Json, if: defined?(::MultiJson) do
   it 'uses multi_json' do
     expect(described_class).to eq(::MultiJson)
   end