OSHI: Offline Messenger

OSHI is a free, open-source, end-to-end encrypted messenger for iOS and Android that uses Bluetooth and Wi-Fi mesh networking to send messages without Internet or cellular service. OSHI does not require a phone number, email address, or account.

Nearby phones running OSHI find each other over Bluetooth Low Energy (about 100 m in the open) and move photos, voice notes and files over Wi-Fi Direct. Messages relay across up to five phones, store-and-forward, and every hop carries only ciphertext: one-to-one chats and calls use X3DH and the Double Ratchet with AES-256-GCM, the same construction as Signal. When any phone gets a connection, queued messages sync over the Internet, Tor, or a covert channel that resembles ordinary HTTPS.

Also included: encrypted voice and video calls, group chats, live location, view-once media, downloadable offline OpenStreetMap maps with routing, an on-device AI assistant that sends nothing to a server, steganography, and a bot API with a Python SDK. An optional LoRa node extends the mesh by kilometres.

The cryptographic core, mesh layer and bot SDK are published under MIT on GitHub; the app shell is not yet published, and there is no public third-party audit yet. Android is distributed as a direct APK (not on Google Play). Built by one developer in Switzerland.