Commit Club

Commit Club is a lightweight social accountability app designed for real-world meetups, like running together in Central Park, group bike rides across the Brooklyn Bridge, or casual NYC community events. The concept is simple: anyone can create a commitment by setting a time, location, stake amount, minimum number of participants required, and a secret check-in code. Friends join by logging in with their email or phone number, instantly receiving a non-custodial wallet via Privy. Each participant contributes the predefined stake, and the funds are held in a smart contract deployed on Flow EVM Testnet. At the event, the organizer shares the secret code, and participants check in on their phone. If the group meets the minimum attendance threshold before the deadline, the contract automatically splits the pooled funds among those who showed up; otherwise, everyone is refunded.

The experience is built to be fun, intuitive, and easy to demo. Joining is frictionless: just scan a QR code, log in with Privy, and confirm participation. Settling the event triggers a celebratory confetti animation on the frontend, making the payout moment playful and memorable. The app is intentionally scoped for hackathon speed — just a minimal Next.js frontend with Privy for onboarding, a single Solidity contract tested and deployed via Hardhat 3, and live interaction with Flow EVM Testnet for on-chain transactions. This structure ensures it qualifies cleanly for all three partner bounties: Flow (by deploying and transacting on Flow EVM), Privy (by delivering a smooth consumer app with embedded wallet auth), and Hardhat 3 (by showcasing proper testing and deployment workflows).

Commit Club stands out by connecting the digital and physical worlds in a way that’s immediately relatable. It takes a simple, concrete behavior — committing to show up with friends — and gives it stakes, accountability, and delight through an approachable Web3 layer. The MVP can be demonstrated in minutes with an NYC-flavored story, making it engaging for both technical and non-technical judges.

Commit Club was built with a deliberate focus on keeping the stack lean, robust, and easy to reason about. On the smart contract side, I used Hardhat 3 as the foundation for development and testing. The contract, written in Solidity ^0.8.24, implements the minimal logic needed for the “create → join → check-in → settle” flow, with careful attention to edge cases like duplicate joins, late check-ins, and refunds versus payouts. Hardhat 3’s improved network simulation made it straightforward to test deadline scenarios and payout logic, giving me confidence in contract correctness before deploying. Deployment targets the Flow EVM Testnet, using its public RPC endpoint and faucet to fund an EVM-compatible wallet. This ensures direct qualification for the Flow Builder Pool Prize while keeping gas costs negligible for iteration.

On the frontend, I built a Next.js app in TypeScript, styled with Tailwind for clean, distraction-free UI. Privy’s React SDK powers onboarding and wallet management: users log in with just an email or phone number, and Privy spins up an embedded wallet under the hood. This hides the complexity of keys and signing, creating the kind of smooth consumer-grade experience that non-crypto friends could use without friction. Transactions like joining a commitment or checking in are signed and sent directly from the Privy wallet to the Flow EVM Testnet. A small set of React hooks abstracts contract calls, keeping the integration tidy and reusable.