A plain GET
The agent requests the resource with no credentials. The server answers 402 with the exact price, the asset and the address to pay.
EMPTOR — caveat emptor, inverted
x402 · open to agents
x402 payment rails for autonomous agents
Buys on its own.
Inside your limits.
An agent can't click “confirm”. Emptor gives it a card that pays per request over x402 — domains, inference, datasets, compute — and an envelope it physically cannot exceed.
The hand presents the x402 card. Move the cursor.
Scroll ↓
The part that lets you walk away.
Paying is the easy half. The half that matters is the one the human owns: what the agent may buy, how much at a time, how much per day, when to stop. Checked before anything is ever signed.
Per purchase15.00 USDG
Per day25.00 USDG
Total envelope50.00 USDG
SettlementRobinhood Chain
Remaining50.00 USDG
domaininference
datasetcompute
transferspayroll
Four categories open, two closed. The agent never sees the closed ones as purchasable. A refusal is returned before a signature is built.
Ask. Get priced. Pay.
x402 revives HTTP 402 Payment Required for machine-to-machine payments. No account, no API key, no subscription. Emptor adds the envelope between the price and the signature.
01 · Ask
02 · Envelope
The human's rules run
Category allowed? Under the per-purchase cap? Under today's cap? Budget left? One 403 and the agent re-plans on its own.
03 · Pay
Same request, with proof
The request is replayed carrying X-PAYMENT. The server verifies, settles, returns the resource and a receipt. Two round trips, no human.
Watch it get told no.
The demo everyone shows is an agent buying something. The one that matters is an agent being stopped, and dealing with it. Second tab.
Demo mode. The 402 challenge, the X-PAYMENT header and the envelope checks are the real shapes, verified against the reference server. On-chain settlement is not wired: every receipt carries "regle": false and nothing here claims a payment occurred.
What it can actually buy.
Anything with a price and an endpoint. These four ship in the reference server, priced per unit, quantity on the request.