Writing down your negative thoughts and then discarding them can help you find peace. Thought Detox lets you mindfully work through those most private thoughts, without storing or sending them anywhere.
(Psst: It's coming to iPhone, too! Get it on the App Store.)
No personal data whatsoever is collected from this app. You'll see that (privacy-respecting) web analytics are provided by Plausible, and you can see exactly what I see on this dashboard.