Custom headers

Use the headers field to forward custom HTTP headers with a request. This is supported for direct (request-based) fetches.

curl https://request.usestring.ai/v1/fetch \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://api.example.com/protected",
    "headers": { "X-API-Key": "abc123", "X-Request-ID": "req-456" }
  }'

Rules

• Header names must be non-empty, contain only letters, numbers, underscores, and hyphens, and be at most 256 characters.
• Header values may be up to 8192 characters.
• Maximum 50 custom headers per request.

Forbidden headers

These headers are managed by the service and cannot be set:

proxy-authorization, proxy-authenticate, proxy-connection, connection, transfer-encoding, content-length, te, upgrade, keep-alive, trailer, host.