Redirect Pro provides a single app embed block inserted to your 404 template. When activated, it tracks the number of visits to 404 error pages on your store, and the URLs that caused the error.
The broken link tracking can be activated or deactivated in your Theme Settings.
https://www.youtube.com/watch?v=-gsP9ZP_B-Y
Note: If you change or update your theme, you need to follow these steps to reactivate Redirect Pro.