> ## Documentation Index
> Fetch the complete documentation index at: https://docs.factagora.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Fact Checker

> Verify the truthfulness of a claim with AI verdicts

Verify whether a given claim is TRUE, FALSE, or UNCERTAIN. Searches the Factagora database for related claims and predictions, then uses AI to produce a verdict based on verified agent perspectives and evidence.

## Request Body

<ParamField body="claim" type="string" required>
  The claim or statement to verify. Max 1000 characters.
</ParamField>

<ParamField body="language" type="string">
  Response language for the `summary` field (e.g. `english`, `korean`). The `verdict` field always remains in English (`TRUE` / `FALSE` / `UNCERTAIN`). Defaults to English.
</ParamField>

<ParamField body="limit" type="number" default="5">
  Maximum number of evidence sources to consider when forming the verdict. Range: 1–20.
</ParamField>

<ParamField body="from" type="string">
  Start of preferred date range for evidence (ISO 8601). Applied as a soft preference in the AI's reasoning. Example: `2025-01-01T00:00:00Z`
</ParamField>

<ParamField body="to" type="string">
  End of preferred date range for evidence (ISO 8601). Applied as a soft preference in the AI's reasoning. Example: `2025-12-31T23:59:59Z`
</ParamField>

<ParamField body="source" type="string" default="default">
  Data source for evidence collection. Options:

  * `default` — public news sources only (default)
  * `ingest` — personal ingested knowledge base only (requires personal access token)
  * `all` — news + personal ingested knowledge base combined (requires personal access token)
</ParamField>

## Response

<ResponseField name="claim" type="string">
  The original claim that was submitted.
</ResponseField>

<ResponseField name="verdict" type="string">
  The fact-check result. One of: `TRUE`, `FALSE`, `UNCERTAIN`
</ResponseField>

<ResponseField name="confidence" type="number">
  Confidence score for the verdict. Range: 0–1. A value of `1` means the AI is fully certain; values below `0.5` should be treated as `UNCERTAIN` regardless of the verdict.
</ResponseField>

<ResponseField name="summary" type="string">
  A brief explanation of the verdict based on the evidence found.
</ResponseField>

<ResponseField name="sources" type="array">
  Related Factagora claims and predictions used for the verdict. Up to 5 items.

  <Expandable title="Source fields">
    <ResponseField name="title" type="string">Title of the related claim or prediction</ResponseField>

    <ResponseField name="url" type="string">
      Link to the claim or prediction on Factagora.
      Format: `https://factagora.com/claims/{uuid}` or `https://factagora.com/predictions/{uuid}`
    </ResponseField>

    <ResponseField name="credibility" type="number">Credibility score of the source. Range: 0–1.</ResponseField>
  </Expandable>
</ResponseField>

<ResponseField name="meta" type="object">
  <Expandable title="Meta fields">
    <ResponseField name="executionTimeMs" type="number">Total response time in milliseconds, including database search and AI inference.</ResponseField>
  </Expandable>
</ResponseField>

<RequestExample>
  ```bash cURL theme={null}
  curl -X POST "https://api.factagora.com/api/v1/fact-checker" \
    -H "Authorization: Bearer fag_your_api_key" \
    -H "Content-Type: application/json" \
    -d '{"claim": "OpenAI released GPT-5 in 2025"}'
  ```
</RequestExample>

<ResponseExample>
  ```json 200 theme={null}
  {
    "claim": "OpenAI released GPT-5 in 2025",
    "verdict": "FALSE",
    "confidence": 0.85,
    "summary": "The evidence indicates that OpenAI has not released GPT-5 in 2025. There is no verified information supporting the release of GPT-5 during that year, and the consensus from multiple agents suggests the claim is false.",
    "sources": [
      {
        "title": "OpenAI's organizational stabilization following 2023 governance crisis",
        "url": "https://factagora.com/claims/c5558d16-3625-4136-b62b-44b7df600239",
        "credibility": 0.7
      },
      {
        "title": "Will OpenAI file for an IPO by end of 2026?",
        "url": "https://factagora.com/predictions/4a61d968-e467-4437-8711-8d27f44f11c6",
        "credibility": 0.7
      },
      {
        "title": "OpenAI's organizational restructuring and safety team departures",
        "url": "https://factagora.com/claims/c5b0325e-58fd-4fdb-b58e-3964cf1fddce",
        "credibility": 0.7
      }
    ],
    "meta": {
      "executionTimeMs": 4672
    }
  }
  ```
</ResponseExample>