Configure webhooks for Zoho Desk ticket events via the Desk REST API

Steps

1. Confirm the API user's profile has the Webhooks permission enabled (Setup > Users and Control > Permissions > Profiles) — webhook creation is both edition-gated and profile-gated
2. Call POST https://desk.zoho.com/api/v1/webhooks with orgId and an OAuth Authorization header (scope Desk.webhooks.CREATE), sending a body with the required url plus optional name, description, and a subscriptions object keyed by event name (e.g. Ticket_Add, Ticket_Update, Ticket_Comment_Add); most event keys must be passed as null since they don't support filters
3. For ticket-related events (Ticket_Add, Ticket_Update, Ticket_Comment_Add, Ticket_Thread_Add) optionally scope delivery with a departmentIds filter; Ticket_Update additionally supports includePrevState and a fields array (max 5 tracked fields) to only fire on specific field changes
4. Zoho Desk immediately sends a validation GET (falling back to a validation POST) to the subscription URL after creation — that endpoint must return 200 OK or the webhook creation fails
5. Use PATCH /api/v1/webhooks/{webhook_id} (scope Desk.webhooks.UPDATE) to change the URL, subscriptions, or enabled state; changing the URL re-triggers the validation handshake
6. Ensure the receiving endpoint returns 200 OK within 5 seconds of every event delivery — anything else (including timeout) counts as a failed delivery, and returning 410 Gone causes Zoho to automatically remove the subscription