Built and maintained rest api endpoints in python (fastapi), backed by postgresql debugged production issues by tracing root causes through application logs and code, not just patching symptoms projects integrated backend services with a react frontend, working directly in a live, multi - developer codebase equipay tatra banka hackathon kotlin, ktor, android/jetpack compose, postgresql, redis, psd2, ai (gemini) full - stack shared - finance app (android + ktor backend) with real psd2 open banking integration against tatra banka's live sandbox built an ai assistant (voice, chat, receipt scanning) that reads app context to answer questions and trigger real actions, like splitting a bill secure auth: jwt with rotating refresh tokens, bcrypt password hashing, redis - backed rate limiting dest platform react, fastapi, postgresql, solidity, websockets web3 real - estate marketplace with a flat 0.5 platform fee model real - time, on - chain auctions with live countdown and anti - sniping protection via websockets connect4 web java, spring boot, postgresql, jwt jwt - based authentication with bcrypt password hashing and secure token - based password reset real - time leaderboard ranking top 10 players by win rate, with match history and star - rating reviews