x402
x402-kit: open-source payments for the machine economy
An MIT-licensed toolkit that implements the HTTP 402 handshake against the live mainnet rail.
Satelink
x402-kit is a small, MIT-licensed toolkit that implements both sides of the HTTP 402 payment handshake: a service that answers unpaid requests with machine-readable payment requirements, and a client that reads those requirements and pays.
It settles in USDC on Base (eip155:8453) and has proven mainnet transactions. Because payment travels in the HTTP request itself, a caller needs no account — a wallet is the only identity.
The repository is public on GitHub. It is the same handshake Satelink's own endpoints use, so anything you build against it works against the live rail.