I store the bare minimum, namely:
a hash value of your email if your signed in;
emails sent via feedback until I reply;
there is no trackers to collect your personal data, all the links i post here are clean.

In order to help you see what you have read, the site stores titles of the pages you visit on your device. It's done using local storage [details]. It's limited to 5Mb and has no expiration date. Right now, you can't turn off local storage.