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What Is a CMS Webhook?

IntermediateQuick Answer

TL;DR

A CMS webhook is an automated HTTP POST request sent from your CMS to an external URL whenever a specific event occurs—such as content being published, updated, or deleted. Rather than polling the CMS API repeatedly to check for changes, external systems register a URL and wait to be notified. Webhooks power event-driven workflows: triggering static site rebuilds on Vercel or Netlify, updating Algolia search indexes, invalidating CDN caches, sending Slack notifications, or syncing content to third-party platforms.

Key Takeaways

  • Webhooks send an HTTP POST to a registered URL when a CMS event fires—no polling required
  • Common triggers include content publish, update, delete, unpublish, and scheduled publish events
  • Primary use cases: static site build triggers, search index updates, cache invalidation, Slack/email notifications, and cross-platform content sync
  • Webhook payloads typically include the event type, document ID, content type, and changed data
  • Secure webhooks with HMAC signatures and shared secrets; implement retry logic and idempotency on the receiving end