API reference
Updated
The REST API is at https://api.faxforagents.com/v1. The reference is built from the server's own OpenAPI 3.1 document, snapshot of 2026-10-30, version 1.3.3. 146 operations in 18 groups and 147 schemas.
How do I read the reference?
- The full reference as plain HTML: every operation, parameter, body, response and schema. Loads with no JavaScript and reads well on a phone.
- openapi.json and openapi.yaml: the document itself, for a generator or a client.
- The interactive explorer below, which loads a third-party viewer on demand.
- github.com/faxforagents/openapi: the same document in a public repository, with a changelog per version.
How do I authenticate?
Authorization: Bearer ffa_test_... or X-API-Key: ffa_test_... on every call. Test keys reach the sandbox, live keys reach the carrier. Signed upload and download URLs take no key. Every mutating call accepts an Idempotency-Key.
Groups
- agents
- identity
- approvals
- auth
- billing
- platform
- extractions
- numbers
- documents
- events
- quotes
- faxes
- inbox
- members
- organizations
- policies
- sandbox
- webhooks
Interactive explorer
The explorer is a 3 MB third-party viewer, loaded only when you ask for it, pinned to one version and checked against its published hash. It reads /openapi.json from this site and lets you try calls with your own key. Your API key goes to api.faxforagents.com and nowhere else.