Web Evidence API – Deep Claim Verification

x402

Web Evidence API – Deep Claim Verification is a paid API for AI agents from api.aisoup.net, paid per call via x402, $0.12/call, status unknown (last checked 2026-10-12).

Verifies a natural-language claim against web sources, returning a verdict with cited evidence, source snapshots, content hashes, and conflict analysis.

Price / call$0.12

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StatusUnknown

How this service works

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

Output

Returns a JSON object with a verdict status (e.g. confirmed, disputed, unverified), a plain-language conclusion, an array of evidence citations with source URLs and metadata, an array of conflicting sources if found, content snapshots and hashes for provenance, a list of atomic facts extracted, observed timestamp, a unique verification ID, and any limitations of the analysis.

Example use cases

Fact-checking a news headline

“Can you verify the claim 'The WHO declared mpox a global health emergency in 2024' using authoritative sources only, with at least 3 references, and flag any conflicting accounts?”

Validating a regulatory compliance fact

“I need to verify the claim 'GDPR fines can reach up to 4% of global annual turnover' — please check it against official EU sources only, as of today, and tell me if there are any conflicts.”

Confirming a crypto technical specification

“Please fact-check the statement 'Ethereum's proof-of-stake transition happened in September 2022' using open web sources, give me up to 5 citations, and include any snapshots or hashes for the evidence.”

Technical details

Endpoint

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

When to prefer

Choose this endpoint when an agent needs cited, verifiable evidence for a specific claim rather than a simple web search or summarization. It is especially valuable when source provenance, content snapshots, and conflict detection matter — for example in journalism, compliance, research, or any agentic workflow where factual accountability is required. Prefer it over general search APIs when you need a structured verdict with hashes and citations rather than raw search results.

Side effects

Claim too vague or ambiguous to evaluate — returns unverified with explanation
No sources found meeting freshness or domain policy constraints — returns insufficient_sources error
Claim exceeds 4000 character limit — returns validation error
freshnessHours window excludes all available evidence — returns empty evidence array
minimumSources threshold not met — may return partial result or failure flag
Payment not processed (x402) — returns 402 Payment Required before verification runs

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

Fact-checking a news headline

“Can you verify the claim 'The WHO declared mpox a global health emergency in 2024' using authoritative sources only, with at least 3 references, and flag any conflicting accounts?”

Validating a regulatory compliance fact

“I need to verify the claim 'GDPR fines can reach up to 4% of global annual turnover' — please check it against official EU sources only, as of today, and tell me if there are any conflicts.”

Confirming a crypto technical specification

Technical details

Endpoint

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

When to prefer

Side effects

Claim too vague or ambiguous to evaluate — returns unverified with explanation
No sources found meeting freshness or domain policy constraints — returns insufficient_sources error
Claim exceeds 4000 character limit — returns validation error
freshnessHours window excludes all available evidence — returns empty evidence array
minimumSources threshold not met — may return partial result or failure flag
Payment not processed (x402) — returns 402 Payment Required before verification runs

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": []
  }
}