{"uid":"cap_F7UhDyA-HFKHrOGR7-Eze","slug":"api-anchor-x402-com-62ad6770","name":"Anchor-X402 Signature Attestation & Dual-Chain Anchoring","description":"Attest a decision: sign (input_hash, output_hash, decision) yourself, or omit the signature and the treasury signs — then dual-chain anchor. Free re-verify at /v1/attest/verify. $0.01 USDC.","url":"https://api.anchor-x402.com/v1/attest","method":"POST","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method","bodyType","body"],"properties":{"body":{"required":["input_hash","output_hash","decision","scheme","signature"],"properties":{"scheme":{"enum":["eip191","ed25519"],"type":"string"},"decision":{"type":"string","maxLength":64,"description":"Free-form short label."},"signature":{"type":"string","description":"0x-prefixed hex (eip191) or base58 (ed25519)."},"input_hash":{"type":"string","description":"64-char hex SHA-256 of the agent's input."},"output_hash":{"type":"string","description":"64-char hex SHA-256 of the agent's output / decision payload."},"signer_pubkey":{"type":"string","description":"Required for ed25519. Ignored for eip191."}}},"type":{"type":"string","const":"http"},"method":{"enum":["POST","PUT","PATCH"],"type":"string"},"bodyType":{"enum":["json","form-data","text"],"type":"string"}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"base":{"tx":"0x...","explorer_url":"https://basescan.org/tx/0x..."},"signer":"0xFE708ED41DE893390240C95A801A49ed8F974702","solana":{"tx":"...","explorer_url":"https://solscan.io/tx/..."},"decision":"APPROVED","signed_at":1746820000,"merkle_root":"10ce4d38b59746febff0651a2d19d5da9a36f4e209e4333414d6d8e4abad898b","signer_verified":true}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.01","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"settled","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":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_Bo2bc_2hWyzUPu6nqpdpc","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Verifies a cryptographic signature over (input_hash, output_hash, decision) and anchors the attestation result to both Base and Solana mainnet for tamper-evident proof.","exampleAgentPrompt":"Verify this signature over my AI decision — input_hash 0xabc123, output_hash 0xdef456, decision 'approved' — and anchor the attestation to both Base and Solana so I have a tamper-proof on-chain record.","exampleUseCases":null,"resultDescription":"Returns a verification result confirming signature validity, plus dual-chain anchor proofs containing transaction IDs on both Base and Solana mainnet, creating an immutable on-chain attestation record of the (input_hash, output_hash, decision) tuple.","failureModes":["Invalid or malformed signature returns signature verification failure","Mismatched input_hash or output_hash causes attestation rejection","Chain anchoring failure if Base or Solana RPC is degraded","Payment not processed or insufficient USDC balance returns 402","Malformed hash format returns 400 bad request","Duplicate attestation of identical tuple may return conflict or idempotency error"],"whenToPreferThis":"Choose this endpoint when you need cryptographic proof that a specific AI decision or computation was made from specific inputs — particularly for audit trails, AI governance, compliance, or any scenario requiring tamper-evident dual-chain notarization of a signed (input, output, decision) tuple. Prefer over a pure hash-anchor endpoint when you also need to verify a signature as part of the same atomic operation.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-13T12:43:50.631Z","isFirstParty":false}