Zync
A BLE-powered proximity social app — discover the right people around you, in real time.
Zync is a proximity-first social discovery app, live on the Google Play Store. Users broadcast their presence over Bluetooth Low Energy and discover nearby people in real time — or search globally — matched on intent: who's looking for a co-founder, a gym partner, a roommate, a chess opponent. The privacy-by-design choice is the core idea: only an opaque user ID goes over the air (u:<id>), and full profiles are fetched securely from the backend, so no personal data is ever broadcast. It's a Flutter app with native Kotlin foreground services that keep BLE advertising and scanning alive in the background (bridged over MethodChannels), on a Node.js/Express + MongoDB backend with Google sign-in and in-app premium.
Highlights
- Shipped to production on the Google Play Store, with the full compliance surface — privacy policy, terms, child-safety standards and account deletion.
- Designed a privacy-first BLE protocol: only an opaque user ID is advertised over the air (u:<id>), and full profiles are batch-fetched securely from the backend — no personal data ever leaves the device unencrypted.
- Wrote native Android foreground services in Kotlin for persistent BLE advertising and scanning, bridged to Flutter over MethodChannels — reliable background discovery, not a foreground-only demo.
- Built intent-based ('seeking') matching across a structured taxonomy — relationships, networking (co-founder, investor, mentor), fitness, sports — with any/all matching and a compact encoded payload for fast filtering and BLE broadcast.
- Delivered two discovery modes — on-device BLE for nearby, backend search for global — with Google OAuth + JWT, hardened Express (Helmet, rate-limiting, validation) and Google Play in-app billing for premium.