cipay

Cipay lets you pay brazilian PIX* invoices with ETH on optimism. Just open the app, scan the invoice qrcode and sign a message.

Example flow. Alice sold her UBI tokens for ETH and wants to pay Pix invoice with it.

• She opens metamask on her phone, scans the invoice.
• The app detects invoice amount in BRL and requests an equivalent amount in ETH + a fee. - She signs a meta transaction sending the amuont to cipay's wallet and sends everything to the backend;
• The backend saves the request locally and broadcasts the meta tx sending ETH from Alice's to cipay's wallet;
• The backend detects that the tx was mined and pays the invoice for Alice with BRL in cipay's bank account.

*PIX is a system free to use system to allow payments and transfers between banks.

A minimally custodial/payment system like this would be impossible without a fast and cheap way to send ETH. Luckily L2s are coming fast. To make this app I used:

• Meta transactions to run business logic before broadcasting the transaction to the network.

• Optimism for fast and cheap ETH (or any token) transfers.

• Starkbank as the bank to finalize the payment.