Android · Ethereum Sepolia · Web3j
FuelSplit is an expense-splitting app where every expense and settlement is recorded on an immutable on-chain ledger — and the people using it never touch a wallet, a token, or a gas fee.
A wallet is generated silently inside the app the first time it opens. Users sign up with a friend code, not a seed phrase.
A treasury-funded faucet backend (Vercel + Upstash Redis) funds each user's transactions automatically, with atomic daily spend caps.
Settlements are recorded on-chain but paid in the real world — UPI or cash. The chain is the referee, not the bank.
Install the app. It generates a wallet, registers you in the
UserRegistry contract, and hands you a
collision-resistant 8-character friend code.
Create a group. The GroupFactory contract deploys a
fresh ExpenseLedger instance just for that group.
"₹3,000 dinner, split 3 ways" becomes a signed transaction. Pairwise balances are net-off on-chain — reverse debts cancel automatically.
A greedy debt-simplification algorithm runs off-chain, collapsing up to N(N−1)/2 debts into at most N−1 payments.
Pay your friend over UPI, mark it settled — the settlement is written to the ledger permanently. Nobody can edit history.
Groups, expenses, balances UI · Web3j 4.9.8 · in-app wallet keystore · retry-hardened transaction sender with gas-estimation fallback
Gas faucet with treasury wallet & atomic daily caps · friend-code
identity (/api/profile, /api/lookup,
/api/fund) · debt simplification runs client-side
UserRegistry — identity & friend codes ·
GroupFactory — deploys one
ExpenseLedger per group ·
ReferralRegistry · pairwise net-balance ledger with
events for every action
Live on Ethereum Sepolia — verify every transaction yourself.
Signed release APK · Android 8.0+
Download FuelSplit APKYou may need to allow "Install from unknown sources" — the APK is signed (v2 scheme) but not distributed through the Play Store.