Web Evidence API – Quick Claim Verification

x402

Web Evidence API – Quick Claim Verification is a paid API for AI agents from api.aisoup.net, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-13).

Verifies a natural-language claim against web sources and returns a verdict, cited evidence, source snapshots, cryptographic hashes, and conflict detection.

Price / call$0.02

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Success—

StatusUnknown

How this service works

Machine-discoverable services AI agents can call and purchase autonomously.

Output

Returns a JSON object containing the verdict status (confirmed/refuted/uncertain), a natural-language conclusion, an array of evidence citations with URLs and excerpts, cryptographic snapshot hashes for provenance, detected conflicting sources, a list of atomic facts, observed timestamp, a unique verificationId, and any noted limitations of the verification.

Example use cases

News headline accuracy check

“I saw a headline saying 'The EU banned single-use plastics in 2021' — can you verify that claim using authoritative sources, show me the cited evidence, and let me know if any sources contradict each other?”

Technical spec confirmation for a dev team

“Our docs say Ethereum's EIP-1559 introduced a base fee burn mechanism — can you verify that claim against official sources with at most 3 citations, and flag any conflicts?”

Regulatory compliance fact-check

“We need to confirm whether GDPR fines can reach up to 4% of global annual turnover — please verify this claim using official sources only, within the EU jurisdiction, and include any conflicting interpretations you find.”

Technical details

Endpoint

POSThttps://api.aisoup.net/v1/claims/verify/quick?utm_source=zero.xyz

When to prefer

Choose this endpoint when you need a cited, machine-readable verdict on a specific factual claim — especially when source provenance, snapshot hashes, and conflict detection matter. Prefer it over general web search when you need structured evidence with a definitive conclusion rather than raw search results, and when auditability (via snapshots and verificationId) is important for downstream trust or compliance workflows.

Side effects

Claim too vague or ambiguous — returns uncertain status with explanation
No sources found within freshnessHours window — returns insufficient evidence
Blocked or allowed domain filters eliminate all viable sources — returns empty evidence array
Claim exceeds 4000 character limit — returns validation error
Payment not completed (x402) — returns 402 Payment Required before processing
Source policy 'official_only' returns zero results for niche topics — falls back to limitations note

Input

Schema · Request body

Field	Type	Description
asOf	—	Optional date at which the claim should be evaluated.
claim	string	The factual claim to verify.
language	string	Preferred response language or auto.
maxSources	integer	Maximum number of evidence sources to return.
jurisdiction	—	Optional country, state, or legal jurisdiction.
sourcePolicy	—	Policy controlling which kinds of web sources may be used.
allowedDomains	array	Optional hostname allowlist without schemes or paths.
blockedDomains	array	Optional hostname blocklist without schemes or paths.
freshnessHours	—	Maximum preferred source age in hours.
minimumSources	integer	Minimum number of evidence sources requested.
includeConflicts	boolean	Whether to search for and report conflicting evidence.

Output

Schema · Response

{
  "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": []
  }
}

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How this service works

Machine-discoverable services AI agents can call and purchase autonomously.

Output

Example use cases

News headline accuracy check

Technical spec confirmation for a dev team

“Our docs say Ethereum's EIP-1559 introduced a base fee burn mechanism — can you verify that claim against official sources with at most 3 citations, and flag any conflicts?”

Regulatory compliance fact-check

Technical details

Endpoint

POSThttps://api.aisoup.net/v1/claims/verify/quick?utm_source=zero.xyz

When to prefer

Side effects

Claim too vague or ambiguous — returns uncertain status with explanation
No sources found within freshnessHours window — returns insufficient evidence
Blocked or allowed domain filters eliminate all viable sources — returns empty evidence array
Claim exceeds 4000 character limit — returns validation error
Payment not completed (x402) — returns 402 Payment Required before processing
Source policy 'official_only' returns zero results for niche topics — falls back to limitations note

Input

Schema · Request body

Field	Type	Description
asOf	—	Optional date at which the claim should be evaluated.
claim	string	The factual claim to verify.
language	string	Preferred response language or auto.
maxSources	integer	Maximum number of evidence sources to return.
jurisdiction	—	Optional country, state, or legal jurisdiction.
sourcePolicy	—	Policy controlling which kinds of web sources may be used.
allowedDomains	array	Optional hostname allowlist without schemes or paths.
blockedDomains	array	Optional hostname blocklist without schemes or paths.
freshnessHours	—	Maximum preferred source age in hours.
minimumSources	integer	Minimum number of evidence sources requested.
includeConflicts	boolean	Whether to search for and report conflicting evidence.

Output

Schema · Response

{
  "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": []
  }
}