LeechBlock requires the following browser permissions to be granted by the user at installation:
- Access browser tabs
- Access browser activity during navigation
- Access your data for all websites
- Download files and read and modify the browser’s download history
The first three of these are required so that LeechBlock can check the URL of each page the browser tries to access (in any tab, not just the active tab) to see whether it should be blocked according to the user’s settings. If the user wants to block pages containing specific words or phrases, LeechBlock also needs to access the content of those pages (not just the URL).
The fourth is used only for the Export Options to File feature (see under General tab in Options). The file is saved using the browser’s download manager.
If the user enters a URL in the Load list of sites from URL field, LeechBlock will ask for additional permission to access external URLs. Most users will not use this feature.
LeechBlock does not send any information to external sites. (This can be confirmed by examining the source code.) All user settings and data are stored locally on the user’s computer (unless the user has chosen to use sync storage; see under General tab in Options). Uninstalling LeechBlock will remove all user settings and data.