GuardianCheckin Public API

A stable, versioned (/v1/) read surface over your listings and forms, with safe form writes. Authenticate with a bearer API key on https://api.gcheckin.com — no GuardianCheckin login required to read these docs.

• Getting started — mint a key and make your first call in under 30 minutes.
• Authentication — the bearer-key scheme and the 401 / 403 / 404 trio.
• Error codes — every error code, its HTTP status, and how to fix it.
• API reference — the full endpoint and schema reference, generated from the OpenAPI contract.

The reference and the error catalog are generated directly from the API's OpenAPI contract, so the docs and the wire format cannot drift. Every example on these pages is executed against the live sandbox in CI.