FactLens API

Evidence checks for your product.

Send audio, video transcripts, images, posts, or individual claims. FactLens retrieves current evidence and returns one structured verdict your application can use immediately.

Get an API key Read the documentation

Terminal

curl https://api.factlens.pro/v1/check \
  -H "Authorization: Bearer fl_live_••••" \
  -H "Content-Type: application/json" \
  -d '{
    "mode": "image_post",
    "claim": "A claim to verify"
  }'

Two checking modes

Use the pipeline that fits the evidence.

Both modes return structured JSON with the claim, verdict, reasoning, confidence, evidence strength, and cited sources.

Audio & video

Submit a transcript directly or include base64 audio for transcription. FactLens extracts a claim, retrieves evidence, and evaluates it in one request.

Images & posts

Submit a claim with an optional base64 image. FactLens combines visual context with current web evidence before returning the verdict.

Simple usage pricing

$10 includes 1,000 requests

Start with any budget from $3. One request is deducted atomically for each accepted check. Tell us what you are building and we will reply with access details.

Documentation

From key to verdict.

Authentication

Send your key in every request. Keys are displayed only when created and stored by FactLens as a SHA-256 hash.

Authorization: Bearer fl_live_your_key

Check a claim

POST JSON to /v1/check. Set mode to audio_video or image_post. Provide claim, transcript, audio_base64, or a supported combination.

{
  "mode": "audio_video",
  "transcript": "The statement to evaluate...",
  "results_per_search": 10
}

Use a UUID in the X-Request-ID header to retry safely without consuming the same request twice.

Usage

GET /v1/usage with the same authorization header.

{
  "request_limit": 1000,
  "requests_used": 124,
  "requests_remaining": 876
}

Errors

401 — invalid, inactive, or expired key.
402 — request budget reached.
400 — invalid mode or missing input.
502/503 — provider request failed or capacity is temporarily unavailable.