{"uid":"cap_AFxfebPiyKiLdigzhPXAZ","slug":"x402-payment-challenge-verifier-d71b99ae","name":"x402 Payment Challenge Verifier","description":"Before paying a stranger's x402 endpoint, read its live payment challenge and compare it against every previous observation. Flags a changed receiving address, network or asset as critical drift. Reports what the endpoint declares; it does not certify the operator.","url":"https://agentic-endpoints-testnet.oliver-835.workers.dev/x402/verify?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"url":{"type":"string","description":"Public HTTP(S) URL of the paid endpoint. Private and loopback addresses are refused, not fetched."},"expect":{"type":"object","properties":{"asset":{"type":"string","description":"Token contract address"},"pay_to":{"type":"string","description":"Address you expect to pay"},"network":{"type":"string","description":"Chain you expect. A name like 'base' and its CAIP-2 form 'eip155:8453' are treated as the same chain."},"max_price_usd":{"type":"number","description":"Refuse-above threshold in USD"}},"description":"Optional. What you believe to be true, typically from a directory listing. Mismatches are reported so you can trust the live challenge over the listing."},"method":{"type":"string","description":"Method used to provoke the challenge: POST (default), GET or HEAD"}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.003","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"registry","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.003/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.003","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.003","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_gIyR9iUbBpAy2QSDs0pVn","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.003","costPer":"request","priority":0,"asset":"0x036CbD53842c5426634e7929541eC2318f3dCF7e","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Fetches the live x402 payment challenge from a target endpoint and flags any drift in receiving address, network, or asset compared to prior observations","exampleAgentPrompt":"Before I pay that x402 endpoint at https://api.example.com/data, check its live payment challenge and compare it against what the directory says — pay_to address 0xABC123, on the Base network, USDC token — and alert me if anything has drifted.","exampleUseCases":[{"title":"Pre-payment address drift check","prompt":"Before my agent pays the x402 endpoint at https://partner-api.example.com/inference, verify its live payment challenge and check whether the pay-to address or network matches what I recorded last week: address 0xDEADBEEF1234, Base network, USDC. Warn me if anything changed."},{"title":"New vendor endpoint vetting","prompt":"I found a new x402 API at https://stranger-api.xyz/v1/compute and the listing says it pays to 0x9F8Cabc on eip155:8453 with a max price of $0.05. Can you read its live challenge and tell me if those details actually match before I trust it?"},{"title":"Automated payment safety guard","prompt":"Before my workflow sends payment to https://data-feed.thirdparty.io/prices, fetch its x402 challenge and flag it as critical if the receiving address, asset, or chain is different from what I configured: pay_to 0xFEED1234CAFE, network base, asset USDC."}],"resultDescription":"Returns the live x402 payment challenge data declared by the target endpoint, along with a drift report comparing it against the expected values you provided. Critical flags are raised for any mismatches in receiving address, network/chain, or asset. The service reports what the endpoint declares without certifying the operator.","failureModes":["Private or loopback URLs are refused and not fetched","Target endpoint is unreachable or returns a non-402 response","Malformed URL input causes rejection","No payment challenge returned if the endpoint does not implement x402","Expected values not provided means no drift comparison is performed"],"whenToPreferThis":"Use this endpoint whenever an AI agent or automated workflow is about to pay an x402-gated API, especially when the endpoint belongs to an unknown or third-party operator. It is the right choice when you want to detect address substitution attacks, verify chain/asset consistency, or enforce a max price cap before committing a payment. Prefer this over blind trust in directory listings when financial safety is a concern.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-12T21:37:33.405Z","isFirstParty":false,"canonicalSlug":"x402-payment-challenge-verifier-d71b99ae"}