HTTP 402 Payments for AI Agents, Explained

HTTP 402 is the web's empty slot. Every time your browser loads a page it gets a number back: 200 means fine, 404 means not found, 403 means forbidden. 402 means "Payment Required", and for roughly thirty years it was written into the rules and left unused. The people who designed the web expected a payment system to arrive and fill it in. None did, until AI agents gave somebody a reason.

Why did 402 sit empty for so long?

Because the web had no money it could actually send. Card payments need a person, a form and a fee floor of a few cents, so a page could not charge you a hundredth of a cent and move on. Sites did the next best thing instead: adverts, subscriptions, "register to keep reading". The status code was a coin slot fitted to a door in the 1990s and never wired up to anything behind it.

What changed?

Two things. Stablecoins - tokens such as Tether that are designed to stay worth about a dollar - made it possible to quote a price in ordinary money. Cheap networks made sending a fraction of a cent cost a fraction of a cent. Put those together and a server can finally answer a request with a price instead of a login screen. The x402 standard, published by Coinbase, is the agreement on how that answer is written down, so any program can read it without a prior arrangement.

Why do agents need this more than people do?

A person who visits one site a few times a day can live with signing up. A program assembling an answer might touch forty sources in a minute and never return to any of them. Accounts and API keys do not scale to that; a price in the reply does. It also hands publishers a middle option between letting AI crawlers take everything free and blocking them outright. Cloudflare has been testing exactly that, charging crawlers per page rather than shutting the door.

None of this asks anything of you as a reader: no wallet starts paying by itself. If you run a site or an API, the practical move is to watch how pay-per-crawl behaves for other people before wiring payments into your own pages. Next, read what x402 is and machine-to-machine payment protocols.