Mass Assign Permission app provides a way to verify whether the permission has been assigned or not. 

Steps to check existing permissions:

  • Go to the tab in Mass Assign Permissions where you want to check existing permissions

  • Fetch field permissions according to your requirement

  • There is a hyperlink on the profile name or permission set name.

  • Click on that profile name

  • It will redirect you to Salesforce's standard permission page where the user can verify the permission.