Thredd does not track your browsing data. It backs up that claim by making all of its code public. However, here are some additional tips on how to protect yourself:
Thredd has privacy settings that can be customized to suit your preferences. The two options are:
Website Blacklist (Recommended) – specify places where Thredd should not run. Note that Google and Gmail are blocked by default.
Only run on click – If you check this box, Thredd will no longer run in the background. You must click the Thredd icon to search for results. While this is the most secure option, your user experience will be worse so Option #1 is highly recommended.