HTTP has carried a '402 Payment Required' status code, unused, for thirty years. On Base it finally means something.
A status code waiting for a use
The number 402 was reserved in the HTTP spec and left empty. Nobody had a fast, cheap way to actually charge per request.
Stablecoins on a low-fee chain changed the math, and the empty slot finally has a job.
Payment rides with the request
The agent calls your API and gets a 402 back with a price. It pays in USDC, and the call goes through. No signup, no key, no invoice later.
The payment is part of the request, not a separate errand.
Why it fits agents
Agents do not fill in checkout forms. They make calls. Pricing the call itself is the natural shape of machine commerce.
Human commerce is a cart and a checkout. Agent commerce is a request and a receipt.
Try it
Our SDK wraps any MCP tool as a paid tool in a few lines. The same flow runs on Arc when you want gas paid in USDC too.
Write the handler once, charge for it everywhere.