Verify API

Stop your agent from citing things that don't exist. One call, one answer, evidence attached.

What it checks

POST /verify/citation

Is this citation real?

DOI or title/authors/year/journal, checked against Crossref & OpenAlex. Flags retractions and mismatched metadata.

POST /verify/url

Does this URL resolve?

Live fetch plus Wayback Machine archival status, redirect chain, content hash, optional expected-content match.

Every response returns confirmed, contradicted, or an honest unknown — never a guess — with the evidence used to decide, so you can check our work:

{
  "verdict": "contradicted",
  "checks": { "exists": true, "retracted": true, ... },
  "canonical": { "doi": "...", "title": "...", ... },
  "evidence": [
    { "source": "crossref", "url": "https://api.crossref.org/works/...", "retrieved_at": "2026-08-30T12:00:00Z" }
  ],
  "latency_ms": 312,
  "cost": { "amount": "0.005", "currency": "USDC" }
}

Get an API key

100 free calls, no card required.

Your API key:
Save this now — it will not be shown again.

Call it

curl https://api.verify.example/verify/citation \
  -H "Authorization: Bearer vk_..." \
  -H "Content-Type: application/json" \
  -d '{"doi": "10.1234/example.doi"}'

No API key? Pay per call instead via x402 (USDC on Base) — send the request with no auth header and follow the 402 payment challenge.

Plans

Free

$0

100 calls/mo, no card

Solo

$15/mo

5,000 calls/mo

Team

$49/mo

25,000 calls/mo

x402 (pay-per-call)

$0.005/call

No account, no key — agents with a wallet pay per request

A failed lookup (our source was down) is always free — we only ever charge for an answer.