Cronofy API vs Zoom Scheduler API

Cronofy API

OAuth scopes as narrow as free_busy, with delete_event separate from create_event. Production pricing starts at $819 a month billed yearly.

Zoom Scheduler API

Each of the 24 operations has its own granular OAuth scope, and Zoom Scheduler and the REST API are separate components on the status page. No operation moves a booking, no official SDK covers Scheduler, and Zoom's API terms forbid benchmarking or monitoring the service.

Cronofy API

1. Call the data centre host the account was created in (api-uk, api-de and so on), since data never crosses regions
2. Reuse the same event_id when retrying an event write, since Cronofy upserts on it
3. Ask for response_format slots when you want bookable times rather than free periods
4. On 423, ask the user to relink, since Cronofy has already emailed them
5. Keep under 50 requests a second and 500 a minute, and pause on 429

Zoom Scheduler API

1. Call GET /scheduler/schedules/{scheduleId}/available_times and book only a spot whose status is available
2. Send start_date_time in ISO 8601 with the booker's IANA time_zone to POST /scheduler/attendee. Expect 409 on a conflict
3. To move a booking, cancel it with PATCH /scheduler/events/{eventId} and status set to cancelled, then book the new slot
4. List scheduled events before retrying a booking, because no idempotency key is documented
5. Request a new Server-to-Server OAuth token every hour. That grant issues no refresh token