api.faxtr.com / v1

Verification infrastructure
for the AI era.

Search 100,000+ verified fact-checks, verify single claims, and guard LLM output against misinformation. One REST API.

# Scan an LLM response for misinformation
curl -X POST https://api.faxtr.com/v1/guard \
  -H "Authorization: Bearer fx_live_xxx" \
  -H "Content-Type: application/json" \
  -d '{"text": "The MMR vaccine causes autism."}'

Introduction

The FAXTR API is a REST service for runtime fact verification. All endpoints return JSON. The base URL is:

https://api.faxtr.com/v1

Currently in private beta. Request access →

Authentication

Pass your API key in the Authorization header. Never expose keys client-side.

curl https://api.faxtr.com/v1/claims \
  -H "Authorization: Bearer fx_live_xxxxxxxxxxxxx"

Quickstart

60 seconds to your first verified claim:

1Sign up at faxtr.com/developers
2Receive your fx_live_* key via email
3Make your first call (snippet above)
4Inspect the response — verdict, evidence, source URL

GET/v1/claims

Search claims

Full-text search across 100,000+ verified claims from 100+ fact-check organizations.

Parameter	Type	Description
q	string	Search query (required)
lang	string	ISO code (en, ko, ja, …)
verdict	enum	true, false, half, disputed
page_size	int	1–50 (default 10)

curl "https://api.faxtr.com/v1/claims?q=vaccine+autism&lang=en" \
  -H "Authorization: Bearer fx_live_xxx"

RESPONSE · 200

{
  "total": 142,
  "page": 1,
  "page_size": 10,
  "results": [
    {
      "id": "clm_abc123",
      "text": "MMR vaccine causes autism",
      "verdict": "false",
      "confidence": 0.97,
      "publisher": "Snopes",
      "review_url": "https://snopes.com/...",
      "verification_method": "external"
    }
  ]
}

GET/v1/claims/:id

Get a claim

Retrieve a single claim with full evidence and dissenting sources.

curl https://api.faxtr.com/v1/claims/clm_abc123 \
  -H "Authorization: Bearer fx_live_xxx"

POST/v1/verify

Verify a claim

Verify a single claim. Returns cached result if available, or enqueues for verification (returns checking).

curl -X POST https://api.faxtr.com/v1/verify \
  -H "Authorization: Bearer fx_live_xxx" \
  -H "Content-Type: application/json" \
  -d '{"claim": "5G causes COVID-19"}'

POST/v1/guardBusiness+

LLM Guard

Scan LLM-generated text for verifiable claims and return a verdict per claim. Designed for runtime guardrails on RAG / chat / agent applications.

curl -X POST https://api.faxtr.com/v1/guard \
  -H "Authorization: Bearer fx_live_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "The MMR vaccine causes autism, and 5G spreads COVID-19.",
    "mode": "strict"
  }'

RESPONSE · 200

{
  "claims_found": 2,
  "results": [
    {
      "span": [4, 38],
      "claim": "MMR vaccine causes autism",
      "verdict": "false",
      "confidence": 0.97,
      "matched_claim_id": "clm_abc123",
      "warning": "Known disinformation"
    },
    {
      "span": [44, 70],
      "claim": "5G spreads COVID-19",
      "verdict": "false",
      "confidence": 0.94,
      "matched_claim_id": "clm_def456",
      "warning": "Known disinformation"
    }
  ]
}

Verdict types

Standardized labels mapped from each source organization's textual rating.

trueVerified accurate by one or more fact-checking organizations

falseVerified as false / fabricated / debunked

halfPartially true, missing context, or misleading framing

disputedOrganizations disagree on the verdict

unverifiableInsufficient evidence to verify

checkingVerification in progress (poll /v1/verify)

Errors & rate limits

Status	Meaning
401	Missing or invalid API key
402	Monthly quota exceeded — upgrade plan
429	Rate limit exceeded — see plan limits
5xx	Server error — retry with exponential backoff

See pricing for per-plan quotas.

Ship verification today.

Free tier — 1,000 calls/month. No credit card required.

Get your API key →