API Overview

The Check API is a RESTful API that allows you to programmatically verify content, retrieve verification results, manage batch jobs, and integrate LLM verification into your applications.

Base URL

All API requests should be made to:

https://api.check.ai/v1

Authentication

All requests require an API key passed in the Authorization header:

Authorization: Bearer vfy_your_api_key

See Authentication for details on obtaining and managing API keys.

Request Format

• Use Content-Type: application/json for all POST/PUT/PATCH requests
• Request bodies should be valid JSON
• All timestamps use ISO 8601 format (e.g., 2024-01-15T10:30:00Z)
• Character encoding: UTF-8

Response Format

All responses return JSON with a consistent structure:

Success Response

{
  "id": "ver_abc123",
  "status": "completed",
  "verdict": "true",
  "confidence": 0.95,
  "decision": "accept",
  "reasoning": "The claim is factually accurate.",
  "paradigmResults": [...],
  "processingTimeMs": 1850,
  "createdAt": "2024-01-15T10:30:00Z"
}

Error Response

{
  "error": {
    "code": "validation_error",
    "message": "Content is required",
    "details": [
      {
        "field": "content",
        "message": "Required field is missing"
      }
    ],
    "requestId": "req_abc123"
  }
}

Available Endpoints

Verification

Batch Processing

Status

HTTP Status Codes

Rate Limiting

Rate limits vary by plan:

Every response includes rate limit headers:

X-RateLimit-Limit: 60
X-RateLimit-Remaining: 45
X-RateLimit-Reset: 1705317060

See Rate Limiting for handling strategies.

Pagination

List endpoints support pagination with these query parameters:

Example

GET /v1/batch?limit=10&offset=20

Paginated Response

{
  "data": [...],
  "pagination": {
    "total": 156,
    "limit": 10,
    "offset": 20,
    "hasMore": true
  }
}

Idempotency

For POST requests that create resources, you can include an Idempotency-Key header:

Idempotency-Key: unique-request-id-12345

• Requests with the same idempotency key within 24 hours return the same response
• Keys are scoped to your organization
• Use UUIDs or unique identifiers from your system

Example

curl -X POST https://api.check.ai/v1/verify \
  -H "Authorization: Bearer vfy_..." \
  -H "Idempotency-Key: order-12345-verification" \
  -H "Content-Type: application/json" \
  -d '{"content": "...", "methods": {"reasoning": 1.0}}'

Versioning

The API version is included in the URL path (/v1). We maintain backwards compatibility within major versions:

• v1 - Current stable version
• Breaking changes will be released under new version numbers
• Deprecation notices will be communicated at least 6 months in advance

SDKs

We recommend using our official SDKs for the best developer experience:

Request IDs

Every response includes an X-Request-Id header with a unique identifier:

X-Request-Id: req_abc123def456

Include this ID when contacting support for faster issue resolution.

Next Steps

• Verify Content - Submit your first verification
• Batch Processing - Process multiple items
• Webhooks - Set up real-time notifications
• Error Handling - Handle errors gracefully