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Concordance Corroboration Checker
x402
Concordance Corroboration Checker is a paid API for AI agents from concordancehq.duckdns.org, paid per call via x402, $0.04/call, status unknown (last checked 2026-10-29).
Checks whether a claim is independently corroborated across multiple unrelated sources, returning a breakdown by source outlet so callers can assess how many independent agencies back the claim.
Price / call$0.04
Success—
StatusUnknown
How this service works
Is a claim independently corroborated across multiple unrelated sources, or does it trace back to a single origin? Groups matches by SOURCE (not category) so a caller sees exactly how many independent outlets/agencies back a claim -- a trust signal no single-source competitor can offer, since it requires already owning many independent sources.
Output
A breakdown of how many and which independent source outlets corroborate the submitted claim, grouped by source (not category), enabling the caller to see exactly how many distinct, unrelated agencies back the claim versus how many trace back to a single origin.
Example use cases
Fact-checking a viral news claim
“I keep seeing the claim that 'Country X deployed troops to the border last week' — can you check how many truly independent outlets are backing that story, not just ones all citing the same wire report? Look at the last 14 days and pull up to 40 sources.”
Due diligence on a company announcement
“A press release says 'AcmeCorp reported record revenue of $2 billion in Q3 2024' — how many independent financial or news sources corroborate that figure? Check since July 2024 with a raw pull limit of 30.”
Verifying a scientific or health claim
“Is the claim 'Regular aspirin use reduces colorectal cancer risk by 20%' backed by multiple independent medical or research sources, or does it trace back to one study? Look back as far as 2020 and pull up to 60 results.”
Technical details
Endpoint
POSThttps://concordancehq.duckdns.org/tools/corroboration?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to distinguish true multi-source corroboration from echo-chamber repetition — i.e., when you want to know how many genuinely independent outlets confirm a claim, not just how many articles mention it. Prefer this over a plain search endpoint when the trust signal matters: verifying news credibility, conducting due diligence, or detecting single-origin misinformation. Use it when source independence (not just volume) is the key metric.
Side effects
- Claim too vague or ambiguous to match any sources — returns zero corroboration results
- Date filter (since) excludes all relevant coverage — empty result set
- Raw pull limit set too low — may miss corroborating sources and undercount independent backing
- Claim is very recent and no sources have indexed it yet — low or zero results
- Claim contains highly domain-specific jargon not indexed in aggregated sources
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| claim | string | |
| since | string | |
| raw_pull_limit | integer |
Tags
x402
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