Expense Splitter

Our project is a decentralized expense-splitting application that makes sharing group costs simple, transparent, and fair. Unlike centralized apps like Splitwise or Venmo, our solution leverages blockchain technology to provide global accessibility, trustless settlement, and Sybil-resistance. Users can create groups (e.g., trips, events, shared households), add expenses, and instantly see who owes what. Balances are calculated and stored on-chain, ensuring transparency and immutability. Settlements are done in stablecoins (like USDC on Polygon), making cross-border payments seamless and low-cost.

This project uses Next.js 15, TailwindCSS and Shadcn for the frontend, along with Wagmi and Metamask to provide a seamless wallet connection experience. The smart contracts are written in Solidity and deployed on Polygon, chosen for its speed and low transaction costs. These contracts handle all the core logic including adding expenses, retrieving balances, and settling payments using stablecoins like USDC. To save time during the hackathon, we also implemented a lightweight “hack” by using smart contract event logs as a receipts ledger instead of building a separate backend database, which gave us transparency without extra infrastructure.