x402 Doctor

Free: after paying an x402 endpoint, pass the PAYMENT-RESPONSE header it returned (X-PAYMENT-RESPONSE in v1). Returns the transaction, network and payer it names, whether that transaction exists on-chain and succeeded, and which USDC moved from whom to whom, with an explorer link. Read-only. Limited to 10 calls per hour.

Free: look up an agent in Concordium's Agent Registry (CIS-8004) by its badge, the CIS-2 token address an Agent Card carries, or by the longer Agent ID that Concordium's registry app shows. Returns whether the badge is valid (Active, the card at agent_uri hashes to the metadata_hash on chain, and that card carries this badge), the owner account (tied to a verified identity), the agent wallet, the origins the card lists, and the CIS-8 key the agent binds with the address it stands for and whether the CIS-8 registry still holds it. To check the payTos of an x402 endpoint against its seller's badge, use x402_payee_check. Read-only. Shares the free limit of 10 calls per hour.

Report a bug, a missing feature or anything else about this service, in a structured way. Free. A person reads every report; nothing is run or changed automatically.

Free: check the signed receipt that every paid x402 Doctor answer carries (diagnose, preflight, batch, deep, fix, delivery check; HTTP or MCP), for example to prove later which verdict you got before paying an endpoint. Pass the whole answer as response. Returns valid, the signer and whether it is an x402 Doctor signer; with route and input also whether the receipt is for exactly that request. A changed verdict or receipt fails. Read-only, nothing is stored. Same as POST /api/v1/verify.

Paid ($0.25 via x402 in USDC on Base, Solana, Monad, Polygon, Arbitrum, Avalanche, Algorand or Stellar, or in RLUSD on the XRP Ledger): not a reading but a purchase. x402 Doctor buys the endpoint once (at most $0.1, USDC on Base, from its own wallet) with the example input its listing declares, checks the answer against the declared output schema, has TypeSafe's Jev judge whether it is what was paid for, and measures the charge on chain. Answers with a job id at once; follow it with x402_delivery_status (free), the result usually comes within minutes. The endpoint must get a "go" from the pre-payment check and be payable in USDC on Base; otherwise it is refused before payment. Same as GET /api/v1/delivery-check. The answer carries a signed receipt (EIP-191, bound to your arguments) that proves later which verdict you got.

Free: the status of a delivery check ordered with x402_delivery_check (or GET /api/v1/delivery-check): awaiting_payment, queued or done, and once done the result: paid_and_delivered, the outcome, the charge measured on chain and the transaction.

Paid ($0.01 via x402 in USDC on Base, Solana, Monad, Polygon, Arbitrum, Avalanche, Algorand or Stellar, or in RLUSD on the XRP Ledger): diagnose an x402 endpoint the way a paying agent would, without paying it: the 402 challenge format, every accepts[] option, the resource URL, Solana settlement readiness, which wallets can pay, Bazaar/OpenAPI discovery and the browser paywall. Returns every check with pass/warn/fail and a fix hint. For the endpoint's owner or a developer debugging it; to decide whether to pay someone else's endpoint, use x402_preflight. Same as GET /api/v1/diagnose. The answer carries a signed receipt (EIP-191, bound to your arguments) that proves later which verdict you got.

Paid ($0.05 via x402 in USDC on Base, Solana, Monad, Polygon, Arbitrum, Avalanche, Algorand or Stellar, or in RLUSD on the XRP Ledger): diagnoses your x402 endpoint, then returns per problem the concrete change as code for your stack (express, next, hono, node, python, generic), filled in with your own payTo, amount, network and route. A working endpoint gets improvements too (ERC-8004 identity, Base Builder Code, x402scan ownership proof, skill.md, browser paywall, Bazaar output schema), each with code. For the endpoint's owner: includes the diagnosis, so there is no need to call x402_diagnose first. Same as GET /api/v1/fix. The answer carries a signed receipt (EIP-191, bound to your arguments) that proves later which verdict you got.

Free: is every payTo of this x402 endpoint really its seller's? Per payment option, one outcome of the draft ERC "x402 Payee Verification for ERC-8004 Agents": verified-wallet (the payTo is the agent wallet registered in the ERC-8004 Identity Registry), verified-delegation (the agent wallet signed an EIP-712 payee delegation for it), mismatch, invalid-delegation, endpoint-unlisted, owner-only (payTo is the identity's owner: never counted as verified), no-agent-wallet or not-read. The identity comes from the 402's extra.erc8004 or the seller's /.well-known/agent-registration.json. When the seller's /.well-known/agent-card.json carries a Concordium badge, the result also has concordium: the agent in Concordium's Agent Registry (CIS-8004; its owner is an identity-verified account) and per payTo verified-wallet, verified-external-key (a CIS-8 bound key), owner-only, mismatch, not-bound, revoked, card-mismatch, endpoint-unlisted or not-read. Never pays. Shares the free limit of 10 calls per hour.

Paid ($0.001 via x402 in USDC on Base, Solana, Monad, Polygon, Arbitrum, Avalanche, Algorand or Stellar, or in RLUSD on the XRP Ledger): call this before your agent pays an x402 endpoint. Returns go, caution or no_go, the recommended payment option, and why: payment would fail, the seller's payout address is on the OFAC SDN sanctions list, over your budget (max_usd), price above what is advertised, not HTTPS, unknown token, its 30-day track record. Never pays the endpoint. The buyer's check for one call; for several endpoints at once use x402_preflight_batch, before a payment above about $1 x402_preflight_deep, and to debug your own endpoint x402_diagnose. Same as GET /api/v1/preflight. The answer carries a signed receipt (EIP-191, bound to your arguments) that proves later which verdict you got.

Paid ($0.005 via x402 in USDC on Base, Solana, Monad, Polygon, Arbitrum, Avalanche, Algorand or Stellar, or in RLUSD on the XRP Ledger): the pre-payment check for up to 10 x402 endpoints at once. Per endpoint go, caution or no_go, the recommended payment option and why, plus totals. For marketplaces and agents that weigh several services. Never pays the endpoints. Same as GET /api/v1/preflight/batch. The answer carries a signed receipt (EIP-191, bound to your arguments) that proves later which verdict you got.

Paid ($0.01 via x402 in USDC on Base, Solana, Monad, Polygon, Arbitrum, Avalanche, Algorand or Stellar, or in RLUSD on the XRP Ledger): for expensive calls. The pre-payment verdict (go, caution or no_go) plus the full diagnosis, the 30-day history per day, how reliable the seller's other endpoints are and whether the endpoint moved domains. Never pays the endpoint. Worth it before a payment above about $1; for an ordinary call x402_preflight is enough. Same as GET /api/v1/preflight/deep. The answer carries a signed receipt (EIP-191, bound to your arguments) that proves later which verdict you got.

Free: does this x402 endpoint work for a paying agent? Returns pass, warn or fail with the number of problems and the top three. Limited to 10 calls per hour. For every check use x402_diagnose ($0.01); for code changes x402_fix ($0.05); before paying someone else's endpoint x402_preflight ($0.001).

Free: add your own paid endpoint to the x402 Trust Index when no registry lists it yet (CDP Bazaar, Circle's Agent Marketplace, GoPlausible, XRPL AI Hub, nohumans.directory, PayAPI Market, MPP directory). x402 Doctor first checks that it answers 402 with a payment challenge (x402, MPP or L402); the next daily scan starts its record, which buyers' agents see before they pay. At most 25 endpoints per host. Limited to 10 calls per hour.

Free: the daily track record of a paid x402 or MPP endpoint from the x402 Trust Index: on how many of the last 30 scanned days an agent could pay it, the latest verdict and reasons, price and networks. found: false when it is not in the index; add your own endpoint with x402_trust_add. Limited to 10 calls per hour. Before paying, x402_preflight ($0.001) checks the live 402 and includes this record.