cipay

Screenshots

Problem Statement

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.

Solution

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.