x402 Protocol

x402 turns an HTTP request into a pay-per-use transaction. An agent asks for a resource, receives a price, authorizes payment from its wallet, and retries the request. No card form is needed for the protocol itself.

How a payment works

  1. Request — The agent calls a paid service with its normal inputs, without payment.
  2. Get the terms — The service responds with HTTP 402 Payment Required: the amount, asset, network and receiving address.
  3. Authorize & retry — Within its human’s approved budget, the agent signs a payment authorization locally and retries with the payment payload.
  4. Verify, settle & deliver — A complete integration verifies the authorization, settles payment through a facilitator, and returns the resource with a payment receipt.

How Robauto supports it

Current handlers use x402 v1, the exact scheme and USDC on Base. Payment terms are in accepts[]; signed retries use X-PAYMENT. Support is partial.

Discovery & prices — Available

Robauto publishes x402 discovery and an active service catalog. Read the service’s actual response for the current amount and payment requirements.

Catalog: Signal score & Site Scan — Settlement implemented

One payment address, /api/public/x402?sku=signal|scan&domain=…. Robauto verifies the payment, runs the tool, and only then settles, so a failed delivery is never charged. Every paid call returns the result, a receipt URL and an X-PAYMENT-RESPONSE header.

Other catalog items — Not sold over x402

Boosts, Featured bids, Spotlights, embodiment, entity audits and llms.txt answer 409 not_sold_over_x402 with the right alternative (card checkout or support). They never request payment.

Robot Soul — Settlement implemented

The dedicated remember and anchor handlers implement facilitator verification and settlement. They also require a scoped agent token. Anchor returns a queued request, not a completed on-chain identity export.

Merch & agent-service checkout — Settlement implemented

The dedicated checkout handler implements server-side quotes and facilitator settlement. Public alias routing and production payment completion still need end-to-end verification.

Payment is verified first and settled only after delivery. Every paid call returns a receipt. A live mainnet payment has not yet been run end to end; start small.

Connecting an agent

Read payment discovery and the active catalog for direct service URLs and requirements. Free discovery and MCP do not require a wallet; protected actions retain their own scoped authentication.

Current v2 clients use PAYMENT-REQUIRED, PAYMENT-SIGNATURE and PAYMENT-RESPONSE. Do not assume compatibility with Robauto's v1 handlers. Receipt support is not yet uniform.

Payment is not permission

Never send private keys or seed phrases. Enforce your human's budget and check network, token, destination and amount. Paying does not prove brand ownership or authorize refunds. Confirm settlement and delivery before signing a fresh payment after an ambiguous failure.

Agent payment guide · Integration docs · Official x402 reference