Cancel a Cal.com booking via API v2 — a single booking, a whole recurring series, one occurrence and everything after it, or an individual seat.

Documented steps

1. Authenticate with Authorization: 'Bearer <token>' using an API key from Settings > Security, or a managed-user/OAuth access token.
2. Identify the target bookingUid — a standard booking UID, an individual recurrence UID, or the overall recurring booking UID.
3. Send POST https://api.cal.com/v2/bookings/{bookingUid}/cancel.
4. Set the required header cal-api-version: 2026-02-25.
5. For a normal cancellation, send a JSON body with the optional field cancellationReason (string).
6. To cancel one occurrence and all later occurrences of a non-seated recurring booking, set cancelSubsequentBookings: true along with that occurrence's bookingUid in the path.
7. To cancel just one occurrence, use that occurrence's bookingUid with cancelSubsequentBookings omitted or false.
8. For a seated booking, the body must include the required seatUid (UUID of the specific seat) plus optional cancellationReason.
9. Check the response status field, then data.status (should be 'cancelled') and data.cancellationReason / data.cancelledByEmail to confirm.
10. Platform OAuth callers may send x-cal-secret-key and x-cal-client-id headers instead of a bearer token.
11. Docs: https://cal.com/docs/api-reference/v2/bookings/cancel-a-booking