NearChat
Overview
NearChat is a mobile messaging app that keeps people connected over Bluetooth mesh when cell networks go down — no internet connection, no SIM card, and no account required.
The Challenge
Cell networks fail exactly when people need them most: natural disasters that take towers offline, remote areas with no coverage, and crowded events where networks overload. Existing messaging apps are useless the moment the signal drops, leaving the people who most need to stay in touch — first responders, hikers, festival-goers — with no way to reach each other.
Our Solution
We built a Bluetooth mesh messaging app where every phone running NearChat extends the network. Messages hop from device to device: a direct connection within 100 meters, multi-hop relay through nearby phones to reach further, and store-and-forward so a message waits until the recipient comes back in range. Contacts are exchanged with a QR code scan instead of a phone number, and every message is protected end-to-end with ChaCha20 encryption.
Project Showcase
Technology Stack
Built for Android and live on Google Play, with iOS in development. The app routes messages over Bluetooth using a multi-hop mesh protocol — direct connection between nearby devices, automatic relay through intermediate phones when the recipient is out of range, and store-and-forward queuing until a path opens up. Every message is encrypted end-to-end with ChaCha20, with Ed25519 signatures for authenticity, and contacts are added by scanning a QR code rather than exchanging phone numbers.
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