For the MetaMask Card Hackathon, we built CircleSplit, a smart contract-based group payment system designed to help users split and settle shared expenses onchain in USDC.
A smart contract that lets any user create a new Ledger, which acts as an onchain group expense tracker.
Other users can join a Ledger and approve USDC payments they’re willing to contribute toward the group expense.
The Ledger owner (or group manager) can edit and configure how the total payment is split among members — supporting custom allocations such as:
- Equal split
- Ratio-based split
- Manual amount per user
Once all members approve, the system executes the USDC transfers onchain from each member directly to the recipient, ensuring transparency and automation.
For users whose USDC is on a different chain, we’ve integrated LI.FI, allowing them to bridge and swap their assets easily to the correct chain before payment execution.
In the future, if MetaMask Card offers programmable payment hooks or external settlement triggers, CircleSplit will automatically:
- Detect card purchases
- Configure the Ledger
- Initiate onchain USDC split and settlement across group members
This will seamlessly connect real-world card spending with onchain group payment management.
- Solidity (Ledger Factory and Ledger contracts)
- Hardhat (development & testing)
- Wagmi + viem + Next.js (frontend)
- LI.FI SDK (cross-chain swap & bridge)