{"uid":"cap_BXyMp520M7l-ycwE2OfYP","slug":"web-evidence-api-claim-verification-1c1e111c","name":"Web Evidence API – Claim Verification","description":"Machine-discoverable services AI agents can call and purchase autonomously.","url":"https://api.aisoup.net/v1/claims/verify?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"asOf":{"type":["string","null"],"format":"date","description":"Optional date at which the claim should be evaluated."},"claim":{"type":"string","maxLength":4000,"minLength":3,"description":"The factual claim to verify."},"language":{"type":"string","description":"Preferred response language or auto."},"maxSources":{"type":"integer","maximum":8,"minimum":1,"description":"Maximum number of evidence sources to return."},"jurisdiction":{"type":["string","null"],"description":"Optional country, state, or legal jurisdiction."},"sourcePolicy":{"enum":["official_only","authoritative","open_web"],"description":"Policy controlling which kinds of web sources may be used."},"allowedDomains":{"type":"array","items":{"type":"string"},"description":"Optional hostname allowlist without schemes or paths."},"blockedDomains":{"type":"array","items":{"type":"string"},"description":"Optional hostname blocklist without schemes or paths."},"freshnessHours":{"type":["integer","null"],"maximum":8760,"minimum":1,"description":"Maximum preferred source age in hours."},"minimumSources":{"type":"integer","maximum":10,"minimum":1,"description":"Minimum number of evidence sources requested."},"includeConflicts":{"type":"boolean","description":"Whether to search for and report conflicting evidence."}}},"responseSchema":{"type":"json","example":{"claim":"The Base mainnet chain ID is 8453.","status":"confirmed","evidence":[],"conflicts":[],"snapshots":[],"conclusion":"Authoritative sources confirm that Base mainnet uses chain ID 8453.","observedAt":"2026-01-01T00:00:00Z","provenance":{},"atomicFacts":[],"limitations":[],"verificationId":"cv_example","providerSources":[]}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.05","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","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":"$0.05/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.05","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.05","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_yfe5dWx3p1ajYDLC-1nHJ","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.05","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Verifies a text claim against web sources, returning a verdict, cited evidence, source snapshots, cryptographic hashes, and conflict detection","exampleAgentPrompt":"Can you fact-check this claim for me: 'The global average temperature has risen by 1.1 degrees Celsius since pre-industrial times' — search authoritative sources only, include up to 5 sources, flag any conflicts you find, and tell me what the evidence says?","exampleUseCases":[{"title":"Journalist verifying a statistical claim","prompt":"I need you to verify this claim before I publish: 'Apple became the first company to reach a $3 trillion market cap in January 2022' — use authoritative sources only, find at least 2 sources, and flag any conflicting information you find."},{"title":"Legal compliance check on a regulatory fact","prompt":"Can you check whether this is accurate: 'GDPR fines can reach up to 4% of a company's global annual turnover' — limit results to official or authoritative sources only, jurisdiction EU, and snapshot the evidence so I have a record."},{"title":"AI agent self-verification of generated output","prompt":"Before I send this to the user, verify this fact I just generated: 'The Base mainnet chain ID is 8453' — open web sources are fine, get up to 3 sources, and tell me if anything conflicts."}],"resultDescription":"Returns a JSON object containing: a verdict status (e.g. confirmed, unconfirmed, contested), a natural-language conclusion, an array of cited evidence items with URLs and excerpts, a list of atomic facts extracted, any conflicting sources, web snapshots with hashes for provenance, a timestamp of when verification was observed, a unique verification ID, provider sources used, and any limitations of the verification.","failureModes":["Claim is too vague or ambiguous for sources to confirm — returns unconfirmed status with explanation","Freshness constraint too tight — no sources found within the requested time window","All candidate domains blocked — returns error if no sources available after filtering","Claim exceeds 4000 character limit — returns 400 validation error","Minimum source threshold not met — returns result noting insufficient sources found","Payment failure via x402/MPP — returns 402 Payment Required","Rate limiting or upstream web access failure — returns 503 or timeout"],"whenToPreferThis":"Choose this endpoint when you need cited, verifiable evidence for or against a specific factual claim — especially when you need source snapshots and cryptographic provenance for auditability. Prefer it over general web search when the output must include a structured verdict, conflict detection, and hash-anchored evidence suitable for compliance, journalism, or agent self-verification workflows. Particularly useful when you need jurisdiction-scoped or domain-filtered verification with freshness controls.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-13T06:33:23.833Z","isFirstParty":false,"canonicalSlug":"web-evidence-api-claim-verification-1c1e111c"}