Phones talk to each other directly over Bluetooth. Your voice hops from phone to phone, so the more people in the group, the further it reaches. Mountains, festivals, deep forest - anywhere with no signal.
 List - who's on, how you reach them, battery |
 Radar - range rings around you |
 Map - the whole group, offline tiles |
 Settings - channel, theme, quick texts |
Each peer shows whether you reach them 📶 over the Bluetooth mesh (with hop count) or 🌐 over the internet relay.
| Talk | Hold the button, your whole group hears you |
| Live | Stream your voice non-stop (works as a baby monitor) |
| Find | An arrow and distance to each friend, like 600 m N |
| See | Map and radar of the whole group |
| Type | One-tap quick texts like OK or On my way |
| Pin | Drop a meet here marker on the map |
| Reach | Out of mesh range? An optional online relay bridges the group over the internet |
Themes
 Corruption |
 Radio |
 Dark |
 Night (red, dark-adapted) |
Default is Field (paper), shown above.
1. Pick a shared channel name (your group's secret word) 2. Walk apart - phones link over Bluetooth on their own 3. Talk. Out of range? Your voice hops through phones in between.
Only phones with your channel name can hear you. Voice is encrypted (AES-256-GCM). No accounts, no servers, nothing leaves the group.
Every setting, explained
Open the ⋮ menu → Settings. Changes save as you go (text fields save when you tap away or press Back).
| Setting | What it does |
|---|---|
| Name | Your display name, shown to everyone else in the group. |
| Channel | The group's shared secret word. Only phones on the same channel hear each other - pick a private one like team-alpha. Defaults to channel-1; a one-tap button resets to it. |
| Quick texts | Your one-tap message presets (up to 8, one per line), shown on the wheel next to the talk button. |
| Theme | Five looks: Field (paper, default), Corruption (brutalist), Radio (white/red), Dark (OLED black), Night (red, night-vision friendly). |
| Share my GPS position | Broadcast your location so friends get your arrow, distance, and map pin. Off = privacy, and the GPS chip is powered down (saves battery). |
| Sound if a device goes offline | Play an alert tone when someone drops off the mesh. |
| Volume-down = push to talk | Hold the volume-down button as PTT - eyes-free, glove-friendly. |
| Mute all sounds | Silence every alert beep and incoming voice playback. |
| Text message sound | Beep when a quick text or message arrives. |
| Live: only stream when speaking | In Live mode, drop silent/room-noise chunks and send only your voice. Off = continuous stream (e.g. baby monitor). Mirrors the Voice det. switch on the main screen. |
| Bluetooth headset mic | Capture your voice through a connected Bluetooth (SCO) headset instead of the phone mic. |
| Hold to ear → earpiece | Proximity sensor routes incoming voice to the earpiece when you raise the phone to your ear - for loud places. |
| Auto level mic (AGC + limiter) | Evens out quiet/loud and near/far speakers without clipping. Applied at your mic, so everyone hears you at a steady level. On by default. |
| Voice quality (AMR-WB) | Bitrate per clip: Sparing (12.65k), Medium (15.85k), Best (23.85k). Higher = clearer but more data; lower stretches weak or long links. |
| Fallback via WiFi → Host | Make this phone the LAN relay server (shares its IP on the mesh) so others extend range over a shared WiFi/hotspot. |
| Fallback via WiFi → Client | Auto-join a host announced on the mesh. |
Online relay (⋮ menu → Servers, separate from Settings): enter an internet relay address to bridge phones that aren't on the same mesh - host:port for a direct/LAN/VPS relay, or wss://your-host for one behind a Cloudflare Tunnel or similar. It reconnects on its own if the link drops. See server/README.md.
The bottom of Settings shows your read-only Device ID and the installed version.
How the relay works, and how to run your own
Phones too far apart for the Bluetooth/WiFi mesh - different cities, no chain of phones between them - can bridge through a shared internet relay.
How it works. The relay is a blind forwarder. Every packet is already AES-256-GCM encrypted on the phone with your channel key, so the relay only ever sees ciphertext - it stores nothing, has no accounts, and just fans each packet out to every other phone connected to it. Whoever runs the box cannot read your voice, text, or position. It's one small Python file (standard library only, no dependencies), dual-protocol on a single port: raw TCP for direct/LAN/VPS use, and WebSocket so it can sit behind an HTTP-only tunnel. A phone connected to both the mesh and the relay bridges the two for free.
Run it
# plain Python 3 - no packages to install
python server/relay.py
# or Docker
cd server && docker compose up -dEnv vars: PORT (default 51820), MAX_CLIENTS (default 64).
Make it reachable - pick what fits your network:
| Situation | How |
|---|---|
| VPS / box with a public IP | Open the port, point the app at your-host:51820 (raw TCP). |
| Home server behind a router | Forward the port to the box, then as above. |
| No public IP / CGNAT / firewall | Run a tunnel that dials outbound - nothing to forward. cloudflared tunnel --url http://localhost:51820 prints a throwaway https://xyz.trycloudflare.com; use wss://xyz.trycloudflare.com in the app. For a permanent hostname use a named Cloudflare Tunnel or Tailscale Funnel. |
Point the app at it. On each phone: ⋮ menu → Servers → Online server, enter the address - host:port for a raw relay, wss://host for one behind a tunnel - and tap Connect. It reconnects on its own (backoff up to 30s) if the link drops.
Full wire protocol, the 200 ok health check, Docker + tunnel deployment notes, and an in-process self-test (python server/test_relay.py) are in server/README.md.
Allow install from unknown sources, then open and grant permissions.
For developers
Native Android (Kotlin, Jetpack Compose, foreground service). A pure-Kotlin core
(com.meshwalkie.core) is JVM-unit-tested; the Android layer wraps Google Nearby
Connections (BLE mesh) with an optional WiFi/LAN relay fallback.
| Area | Tech |
|---|---|
| Transport | Google Nearby Connections (P2P_CLUSTER, BLE), TTL + dedup flood |
| Voice | AMR-WB (MediaCodec), IMA ADPCM fallback, live chunk streaming |
| Crypto | AES-256-GCM channel key |
| Map | osmdroid (OpenStreetMap, no API key) |
| UI | Jetpack Compose |
# Build
gradlew.bat :app:assembleDebug
# Unit tests (pure JVM core)
gradlew.bat :app:testDebugUnitTestRadio behaviour cannot be unit-tested; verify on 2-3 phones (same-room
discovery, arrows, PTT, multi-hop relay, freshness, screen-off). A signed
release needs a keystore.properties at the repo root pointing at your own
keystore; that file and all *.jks keys are gitignored and never committed.
Online relay - phones off the same mesh reach each other through a
standalone internet relay (blind ciphertext forwarding, no accounts, same
length-framed wire protocol as the phone-hosted relay). See
server/README.md for the protocol spec, how to run it
(plain Python or Docker), and deployment notes.
Fonts - the FIELD and CORRUPTION themes bundle Doto, VT323, and
Silkscreen (Google Fonts, SIL Open Font License) under
app/src/main/res/font/ for their dot-matrix/pixel type scales. Licenses in
docs/font-licenses/.