Event Subscription webhook never delivered — no CRC validation attempt, endpoint confirmed working

API and Webhooks Cloud Recordings
1

API Endpoint(s) and/or Zoom API Event(s)
recording.transcript_completed, meeting.started (added as a second test event)
Event Subscriptions feature, General app (User-managed, Development)

Description
I’ve configured an Event Subscription with a webhook endpoint, and the subscription saves successfully and shows as active (Apps on Account shows 1 subscription). However, Zoom never delivers anything to the endpoint — not even the initial endpoint.url_validation CRC handshake. My app’s own Event logs tab is completely empty for any time range, confirming zero delivery attempts were made from Zoom’s side.

I’ve independently confirmed my endpoint is working correctly by manually replicating Zoom’s CRC challenge payload and sending it directly — it correctly returns the expected response. So this doesn’t appear to be an issue with my endpoint itself, but rather with Zoom never attempting delivery in the first place.

Error?
No error is shown anywhere in the Zoom UI — the endpoint URL saves cleanly with no validation failure message. There is simply a complete absence of any delivery attempt.How To Reproduce
Steps to reproduce the behavior:
1. Request URL: https://iscribehealth.app.n8n.cloud/webhook/zoom-transcript-completed
Method: POST
Body (sent manually to test):

{
“event”: “endpoint.url_validation”,
“payload”: { “plainToken”: “<random_token>” },
“event_ts”:
}

2. Authentication method / app type: General app, User-managed, Development environment. No auth on the endpoint itself (Authentication: None), matching Zoom’s expected CRC flow.

3. Any errors: None shown — subscription saves without error, but Event logs show zero entries. Already tried: toggling the Event Subscription feature off/on, deleting and fully recreating the subscription, and testing with a second unrelated event type — no change in any case.

2

The main clue is that Zoom never sent endpoint.url_validation. For Marketplace/build-flow webhooks, Zoom requires you to manually trigger the initial webhook validation by clicking Validate under the Event Notification Endpoint URL. Simply saving or enabling the subscription is not what initiates the CRC. The endpoint must return the challenge response within 3 seconds.

If you want an alternative way to receive Zoom meeting data without maintaining the webhook and recording pipeline yourself, Recall.ai’s Meeting Bot API handles meeting capture across Zoom and other platforms. It can also simplify transcript ingestion workflows.