A real-time blood donation app that connects donors and seekers nearby, with a search radius you can adjust from 5km up to 50km.
- 🎥 Video Demo: YouTube
Most directory-style apps just list every donor in a city. BloodZone instead uses MongoDB's 2dsphere geospatial indexing to run targeted queries that actually narrow things down:
- Distance-based search: Finds donors within a radius the requester chooses (5km, 10km, 20km, or 50km) using
$nearqueries. - Eligibility check built in: Automatically skips donors who gave blood in the last 3 months, so requesters only see people who can actually donate right now.
Authentication runs through a server-side Google OAuth 2.0 flow, designed so sensitive tokens never touch the client:
- The raw auth code from Google is exchanged on the backend, not the frontend.
- Sessions are managed with a custom JWT setup (access + refresh tokens), so users stay logged in securely without constant re-authentication.
Donors and seekers can message each other instantly through Socket.io, with authentication enforced at the connection level:
- A custom handshake middleware checks the JWT access token before a socket connection is allowed to open.
- This keeps the chat closed to verified users only. So no anonymous listeners, no spam connections.
| Layer | Technology | Key Use Case |
|---|---|---|
| Frontend | React Native (Expo) | Android (verified), iOS (beta) |
| Backend | Node.js + Express | REST API |
| Database | MongoDB (Mongoose) | Geospatial indexing & data storage |
| Real-Time | Socket.io | Bidirectional, event-based messaging |
| Auth | Google OAuth + JWT | Secure identity management |