Make a professional USDC invoice in a minute, send the link, and watch it flip to Paid the moment the transfer lands on-chain. Your client pays from any wallet — we never touch the money.
Create a free invoice → How it worksYour details, client, line items, due date. Everything stays in your browser.
The whole invoice is encoded in the link. Your client sees a clean invoice, a QR code, and a one-click “Pay with wallet” button.
Each invoice carries a unique amount fingerprint, so the page can find its exact payment on-chain and show the transaction as proof.
No. Payments go straight from your client's wallet to yours. opnaco is a static web page; there is no backend that could touch money or data.
In the link itself (compressed into the URL fragment, which browsers never send to servers) and in your browser's local storage for your history.
Every invoice amount gets a tiny unique fingerprint in its last decimals (e.g. 1,500.003417 USDC). The page asks a public RPC node for USDC transfers to your address since the invoice was created and matches that exact amount.
Send 29 USDC to the opnaco treasury from any wallet, then paste the transaction hash. The app verifies it on-chain and unlocks Pro in that browser. Keep the hash — it's your license and works on any device.
Email opnaco@proton.me with the wallet address you paid from and we'll find it on-chain.
Native USDC (Circle) on Base, Arbitrum, Optimism, Polygon and Ethereum.