Hey Product Hunt — I'm the solo dev behind Red Grid Link. Red Grid Link started as a side project called Red Grid MGRS — a simple MGRS navigation app I built because I was tired of converting grid coordinates by hand in the field. But every time I showed it to people, the first question was always the same: "Can my team see each other on the map?" So I built Field Link. The technical approach is a bit unconventional: instead of standing up a server, I went with Bluetooth Low Energy + WiFi Direct for the transport layer, AES-256-GCM for encryption with a proper ECDH key exchange, and CRDTs for state sync so there's no single point of failure in the mesh. Every device is equal — no "host" required after session creation. The hardest part was making BLE reliable across iOS and Android simultaneously. Apple and Google have... different philosophies about Bluetooth, let's say. The CRDT sync engine was the fun part — position updates are delta-compressed to under 200 bytes each, so the narrow BLE pipe isn't a bottleneck. The app is live on the App Store now with Android coming shortly. I'm a one-person team, so feedback goes directly into the next sprint. Curious to hear from this community: has anyone else tried building real-time sync over BLE? What was your experience with cross-platform Bluetooth reliability? I'd love to compare notes.

Red Grid Link

Encrypted Bluetooth team tracking. No servers needed.

Encrypted Bluetooth team tracking. No servers needed.