Notion Watch

About

One of the limitations of Notion is its lack of support for webhooks, which makes it almost impossible to track when a page is changed.

Notion Watch adds a watcher to Notion in your web browser and pings your configured endpoint each time it detects a change.

The extension also adds a Sync button to Notion's topbar. You may optionally disable the watcher and rely on the button to trigger pings manually.

Notion Watch is an open-source project. You may fork it to add your own desired features or adapt it for a different browser: 
https://github.com/nortta/notion-watch