FairPay splits any bill and tracks who has paid, checking every payment on Monad. At FairEats restaurants, guests order from the table, split the bill and can pay without linking their wallet.
The app runs on a free server, so the first visit can take about 50 seconds to wake it up.
No account or email. You sign in with a wallet signature. It costs nothing and sends no transaction.
Checked on-chain. A share counts as paid only once FairPay finds the payment on Monad. Public payments link to their transaction on the explorer.
Testnet and unaudited. Test USDC only, with no value. Never send real funds to a FairPay wallet or contract.
Independent project. Built on Monad, not made or endorsed by the Monad Foundation. About FairPay
No wallet handy? Try the simulated table demo. It runs in your browser and moves no money.
Evenly, by exact amounts, by percent or by shares. Leftover cents land in a stated, predictable place.
Send it to the group. Friends without a wallet get a name-only seat and claim it when they sign in.
A share shows as paid only after FairPay finds the payment on Monad. Nobody can just tick a box.
At verified businesses you can pay through a privacy pool, so your wallet isn't linked to the payment.
A trip, a dinner, the rent. Create a bill, send one link, and watch the shares come in.
Enter what it was for and the total in USDC, then add people from your friends, by wallet address or by name. The preview shows every share before you save.
Copy the bill's link into your group chat. It shows names and amounts, never wallet addresses. Anyone added by name claims their seat from the link.
Each person pays their own share from their own wallet, in test USDC on Monad. Send a reminder to whoever hasn't paid yet.
Each share turns Paid once FairPay finds the payment on-chain. Mark anyone who paid you some other way as Covered. When nothing is left to collect, the bill is settled.
One person paid? At a restaurant, one guest can pay the whole bill and then split it with friends from the order page. The others settle up with them through FairPay.
FairEats is the restaurant platform inside FairPay, under Business. Restaurants list their menu and tables; guests order from their phones and each pays their own share.
When a bill is fully paid, FairEats numbers and issues the invoice. With a GSTIN it is a Tax Invoice with CGST and SGST (or IGST), place of supply, SAC codes and the amount in words; without one it is a Bill of Supply. Each invoice has its own link and prints cleanly.
Amounts are in test USDC. Saffron Table is a demo restaurant with a demo GSTIN.
Private (the app calls it Confidential) doesn't mean invisible. It means the chain can't connect your wallet to this payment.
It works when you pay a verified business, such as a FairEats restaurant whose payout wallet is on the pool's allowlist. Bills between friends are paid publicly.
Your wallet
Adds 5 USDC notes to the pool. This step is public.
Privacy pool
Holds your notes among everyone else's.
Your browser
Builds a zero-knowledge proof that you own a note.
Relayer
Sends the payment and pays the gas. It can refuse, but it can't redirect it.
Restaurant
Gets paid. FairPay verifies the payment on-chain, like any other.
| What is recorded | Public payment | Private payment |
|---|---|---|
| Your wallet address | In the payment | Only in the earlier top-up, not in the payment |
| The amount | Visible | Visible (always whole 5 USDC notes) |
| The restaurant's address | Visible | Visible |
| What you ordered | A reference code only | A reference code only |
| Which top-up paid | Not applicable | Hidden among the other deposits in the pool |
Privacy here is from the public chain. FairPay's server still sees your connection (for example your IP address), and a small pool means a small crowd to hide in. Add notes well before you pay.
Real payments with test USDC, made with the contracts below. Open any of them on the explorer and check who sent it.
| Payment | Transaction | Sent by | Sent to |
|---|---|---|---|
| PublicA share of a bill, paid from the guest's own wallet | 0xa96621a0e8ba54c5d1b16c5a709112acde78b55cb4762f7be8c0f2b7d7eaccaa (transaction on the Monad explorer, opens in a new tab) | Guest wallet 0x1384675b3b293f3a71bf121525874b983c34c4b7 (Guest wallet on the Monad explorer, opens in a new tab) | FairPay router |
| PrivateA FairEats order at Saffron Table, paid confidentially with one 5 USDC note | 0x867c10b854aaf3bd21cd2a4bf3098e0690cd120972719ab864c249d8e7d6d4d1 (transaction on the Monad explorer, opens in a new tab) | Restaurant relayer 0x6f1ef92e0d6eb2428558781b5d87cfee19164266 (Restaurant relayer on the Monad explorer, opens in a new tab) | Privacy pool |
Unaudited testnet software with test USDC. Don't use it with real money.
@fairpay/sdk does the payment and the check. Your backend creates a reference, the browser pays, and your backend verifies against the chain before it releases anything.
const result = await fairpay.verifyPaymentTx(
deployment,
publicClient,
{
txHash, orderRef, merchant,
amount: share.amount,
expectedPayer: share.wallet, // public payments only
minConfirmations: 2n,
},
)
if (result.status === "verified") releaseOrder(shareId)Sign in with a browser wallet or the built-in test wallet, get test USDC from the faucet, and create a bill. It's free, and nothing on testnet has value.