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Website | Architecture | FAQ | Terms of Service | Privacy Policy | Support

Airhop is an iOS + Android app (macOS and Windows coming soon) for private, offline-first peer-to-peer communication over Bluetooth mesh networks, with Nostr internet bridging and Cashu ecash payments. Our mission is to make censorship-resistant communication available to anyone: during natural disasters, internet blackouts, mass protests, or any situation where networks are unavailable, surveilled, or shut down.

Built on the foundation of bitchat, using the same BLE wire protocol, and service UUIDs, meaning Airhop-installed devices can automatically discover and join the same mesh as nearby Bitchat-installed devices, relay messages, and exchange DMs with zero setup. Airhop also extends the protocol with Double Ratchet forward secrecy, Tor on both platforms, offline ecash payments, and offline AI (not present in bitchat at the time of writing).

TL;DR: No internet required. No central servers. No accounts. No tracking.

Airhop chooses a transport per message. Bluetooth is the only one that needs no internet and the only one that works across iOS and Android. WiFi and Nostr are used when they are available.

Notes on the numbers:

• Text messages (channel and DM) are tiny and effectively instant on any transport. Throughput only matters for files.
• The ~19 KB/s figure is 467 bytes per fragment sent one every 25 ms. The delay is required: without it the radio drops fragments and the transfer never completes.
• A channel attachment paces at 30 ms instead (~16 KB/s), since each broadcast fragment requires one radio write per connected peer, increasing airtime usage as the room grows.
• WiFi currently shares that same paced queue, so it runs at the same speed as Bluetooth for now. [ Lifting the cap is planned ]
• A 1 MB file (the per-file cap) takes about 56 seconds to one peer. Attachments are capped at 1 MB for bitchat compatibility and to keep transfers short. [ Increasing the cap is planned ]
• Android WiFi Aware and iOS MultipeerConnectivity are different protocols and cannot connect to each other, so the WiFi path only works Android to Android or iPhone to iPhone.
• Nostr relays carry small signed events, not file bytes. Files can be shared over Nostr only by uploading them to a separate HTTP host and posting a link (NIP-96). Airhop does not do this: that host is a central server that can log, throttle, or take down your files, which is exactly what this app avoids. Attachments therefore travel only over Bluetooth or WiFi.

Timing intervals:

Offline and private messengers generally fall into three categories:

• Internet-only messaging apps that rely on online infrastructure and cannot communicate locally without internet access.
• Radio-based mesh networks that work offline but require dedicated hardware.
• Phone-to-phone mesh apps that use Bluetooth and WiFi on devices people already own.

Airhop belongs to the third category and extends it with a Nostr-based internet layer for long-distance communication when connectivity is available. The table is grouped in that order, starting with the apps most people already measure private messaging against.

⚠️ Threema's client apps are open source, but its servers are not, and the app is a paid one-time purchase.

Signal and Threema are here as the benchmark rather than as alternatives. Both are excellent at what they do, and neither is trying to work without a network: Signal ties an account to a phone number and Threema to a Threema ID, and both stop entirely when the network does. Airhop is aimed at the moment after that, when there is no network to be excellent on.

git clone https://github.com/areebahmeddd/airhop
cd airhop
npm install

rm -rf ios/Pods ios/build ~/Library/Developer/Xcode/DerivedData/Airhop-*
npx pod-install
npm run ios

cd android && ./gradlew --stop
rm -rf ../node_modules/expo-modules-core/expo-module-gradle-plugin/{build,.gradle}
./gradlew app:dependencies --write-locks
./gradlew app:assembleDebug -Pkotlin.incremental=false
cd .. && npm run android

Airhop would not exist without the work of the bitchat community. Thank you to everyone who built the foundation this project stands on. Their work is released into the public domain under the Unlicense.

Help keep the project going by donating via the website, sponsoring on GitHub, or simply giving this repository a star. What the project needs funding for is published as a funding.json manifest, following the funding.json standard.