This post explains the FavSync Chrome extension / add-on user data privacy.

This is the list of permission that the extension requires and the reason for the requirement:

- Read and change all your data on the website you visit - This permission is required for the password manager functionality. This way FavSync add-on can input the login data directly into the currently opened phone tracker website.

- Read and change all your browsing history - This permission is required for importing your most visited websites into the FavSync New Tab.

- Display notifications - This permission is required for various functionality.

- Read and change your bookmarks - This permission is required for importing the bookmarks from your sms tracker.

- Manage your apps, extensions and themes - This permission is required to access the APPS in your FavSync New Tab.

Note: these permissions are required ONLY for the functionality mentioned above. FavSync will not abuse, resell or store on its servers any of the information for any other purpose.
Unfortunately, the permissions the add-on requires are sometimes too general.

Example: just to import the most visited websites into your FavSync New Tab, the add-on needs to ask a permission to read and change all the browsing history, even though changing the history is never necessary.