x402 · HTTP payment simulation

An AI agent requests a paid resource. The server replies 402 Payment Required with price terms; the agent signs a gasless EIP-3009 transfer; a facilitator verifies and settles it onchain in USDC; the server unlocks the resource. Try censoring the facilitator to see the standard's single centralization point.
AI agent requests resource API server 402: pay $0.01 USDC Signed payload EIP-3009 auth Facilitator /verify + /settle CENSORING USDC contract transferWithAuthorization
Requests / 402s
0
Payments settled
0
USDC volume
$0.00
Resources delivered
0
Parameters — edit me
$0.010
3.0/s
8
2%
Controls

Illustrative simulation. Models the x402 challenge-response flow: 402 response with payment terms, a signed gasless EIP-3009 authorization, facilitator verify/settle, and onchain USDC transfer before resource delivery. The censor button shows the real structural risk noted in the mechanism review — most flow currently routes through one facilitator, a de facto chokepoint despite the protocol being permissionless. Traffic and pricing are randomized for visualization, not live onchain data. Part of The Onchain Experiment Atlas.