Privacy
No cookies, no accounts, no ad trackers. Your lesson progress stays in your own browser. Here is exactly what the site stores and counts.
The short version
- No cookies. The site sets none, and no third party sets any through it.
- No account. You do not sign up. Nothing identifies you.
- Your progress stays on your device. XP, streak, finished lessons and the skills to review are saved in your browser's local storage. They never leave your device. Clearing your browser's site data deletes them.
What we count
To know which pages and lessons are useful, the site sends anonymous counts to its own server:
- a page was viewed, with the page address and the kind of site you came from (for example "a search engine");
- a lesson was finished, with the lesson's name;
- a calculator was used, with the calculator's name;
- a milestone was reached the first time (for example "20 exercises done").
These counts are added to daily totals. No IP address, cookie, device identifier, user agent or full referring address is stored. We also count visits from search and AI crawlers by their name.
Fonts
The fonts are served from this site's own server. No page loads anything from a third party: no font service, no analytics script, no ads, no social widgets.
Contact
Questions about privacy: write through the contact details on the About page.