Ethereum Wallet (GoPay)

Full-stack crypto wallet built in 36 hours for a technical hiring assignment.

GitHub
Node.jsExpressPostgreSQLEthers.jsFlutterJWT

A complete Ethereum wallet built in 36 hours as a hiring challenge - featuring a JWT-secured Node.js backend and a Flutter mobile app for Sepolia testnet transactions.

The Challenge

Build a functional crypto wallet with key management, transaction signing, and blockchain integration - despite zero prior experience with Ethereum tooling - and deliver it in under two days.

Key Decisions & Tradeoffs

  • Rapid stack mastery: learned Ethers.js, wallet key handling, and Sepolia RPC endpoints under extreme time pressure.
  • Fallback resilience: implemented retry logic for unstable public RPC nodes to keep transactions reliable.
  • Security baseline: used JWT for auth and PostgreSQL for encrypted private key storage, with keys never exposed to the frontend.

Outcome

One of the few candidates to fully deliver a working wallet against the assignment brief - proof of rapid full-stack execution under real time constraints.