The open source tool shows you which data collection purposes you have (unwittingly) agreed to on websites such as Google or Facebook. You can then change the settings quickly and easily.
I didn't even know that I somehow had "allowed" Facebook to do face recognition. With this tool, I stopped that instantly.
Pros:Facebook, Google and others hide their better privacy options behind a wall of complexity. This tool makes settings visible and actionable
Cons:Doesn't support all websites