For decades, 402 Payment Required was the web's most famous dead letter. There was no standard way to act on it, so nobody sent it. Agents change the economics.
The flow
An agent hits a metered endpoint. Instead of a key check, it gets a 402 with a price quote. The agent's payment middleware settles the micropayment and replays the request with proof attached. The endpoint returns 200. No dashboard, no monthly invoice, no procurement.
GET /v1/search?q=... -> 402 Payment Required
settle( quote ) -> receipt
GET /v1/search?q=... -> 200 OK (X-Payment: receipt)Why agents make it work
Humans hate per-action payments — the friction is unbearable. Machines don't. For an agent, settling $0.0003 for a search call is just another step in the loop.
- No subscriptions to long-tail APIs you call once.
- Providers meter real usage instead of guessing at tiers.
- Budgets and caps keep autonomous spend bounded.
Aperture handles the 402 handshake for you across every endpoint in the marketplace.
Written by Maya Chen
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