Lost & Found: Campus Mobile App

College campuses lack a unified directory for lost items. Students usually post details on random chat groups, which are disorganized and lack search functionality. As a result, items like keys, IDs, and earphones are rarely returned to their rightful owners.

A successful mobile solution needs to support image uploads, geographical tagging, real-time message alerts, secure backend verification, and direct authentication to verify campus membership.

I built a mobile lost-and-found system using React Native, a Spring Boot Java REST API, and Supabase:

• React Native Client: Developed a cross-platform mobile client with Expo, utilizing TypeScript and Shopify FlashList for fluid list scrolling.
• Spring Boot API: Built a backend REST server in Java/Spring Boot to handle business logic, geo-radius matching query computations, and notification triggers.
• Database & Storage: Leveraged Supabase (PostgreSQL) for structured metadata storage and Cloudinary for high-performance image hosting, compression, and dynamic format optimizations.

A major backend challenge was managing secure session authentication and token validation. Instead of exposing database tables directly, we routed critical workflows through the Spring Boot API, validating incoming requests against JWTs issued during user login and handling custom token rotation cycles.

On the client, we faced poor page rendering performance when listing items. Rendering high-resolution pictures uploaded by users consumed excessive device memory and caused screen lag during fast scrolls.

I solved this by writing a compression function that intercepts uploads on the mobile client, reducing images to <200KB and using Cloudinary's dynamic resize and format conversion APIs (delivering optimized WebP/AVIF formats based on client capabilities) before rendering them.

Additionally, I replaced standard React Native ScrollView lists with FlashList from Shopify, which recycles cells and memory, and wrapped images in caching containers to prevent redundant network fetches.

Related Reading: Interested in how modern authentication models secure client-server communication? Check out my guides: JWT vs Sessions: What I Learned Building Apps and My First OAuth 2.0 Integration: From Zero to Production.