The short version. You can use every course without an account. If you sign in, we store just enough to save your progress across devices, and we only email you about new courses if you tick the box. No ads, no trackers, and we never sell your data. You can delete your account at any time.
Without an account
Your progress, position and settings (such as reading speed and voice) are saved in your own browser's local storage. They never leave your device.
When you sign in
We store:
Your profile: your name, and your email address. If you sign in with GitHub, also your GitHub username, user ID and avatar URL. We ask GitHub only for your public profile and your email addresses, never your repositories. The access token GitHub returns is stored encrypted, and we don't use it after you sign in.
Your progress: which sections you finished, and the section and step you were on, per course.
Sign-in data: a session that keeps you signed in for 30 days, with the IP address and browser it was created from, and one-time email sign-in links, which expire after 15 minutes and are stored only as hashes. To limit abuse we also keep short-lived counters of sign-in attempts per IP address.
Your email choice: whether you asked to hear about new courses, and when.
Emails
We send sign-in links when you ask for them. We only email you about new courses if you opted in, and you can switch that off any time from the account menu.
Cookies
Signing in sets a session cookie (better-auth.session_token) that keeps you signed in. During GitHub sign-in a short-lived cookie protects the sign-in from forgery and is removed when it finishes. There are no analytics or advertising cookies.
Where it lives
The site and its database run on Cloudflare. Emails are sent through Cloudflare's email service. GitHub handles GitHub sign-in.
Deleting your data
Open the account menu and choose Delete my account. That permanently removes your profile, progress and sessions. Progress saved in your browser stays until you clear it, or you can use Reset my progress in a course's settings.