Privacy Policy

What we collect

• Account data: your name, email address and a one-way hash of your password (we never store the password itself). If you sign in with Google, we receive your Google account ID, name and email address from Google, and nothing else.
• Payments: if you subscribe to Pro, payment is handled by Stripe. We never see or store your card details; we keep your Stripe customer ID and your subscription's status and renewal date.
• AI tutor: if you use it, your questions, the lesson you're on and your current simulation settings are sent to an AI model provider through the Vercel AI Gateway to generate the answer. We don't store the conversation.
• Emails: account emails (address confirmation, password reset, and streak reminders if you turn them on) are delivered through our email provider, Resend.
• Learning data: which lessons you've opened or completed, your answer to each quiz question, solved practice problems, XP and streak, and your time zone (so your streak rolls over at your midnight).
• Session data: a hashed session identifier and your browser's user-agent string, so you can see and sign out of your devices.
• Usage statistics: anonymous, cookieless page-view counts (page, referrer, country, device type) through Vercel Web Analytics. These aren't linked to your account.
• Error reports: when something breaks, technical details about the error (the page, browser and stack trace) are sent to our error-tracking provider, Rollbar, so we can fix it.

Cookies

We use one essential, httpOnly cookie to keep you signed in (and, during Google sign-in, a second one that lasts ten minutes to protect the sign-in from forgery), plus one that remembers your language if you choose one. We store your light/dark theme preference in your browser's local storage, and, if you try a quiz or practice problem before creating an account, those results too (they move into your account when you sign up, and are then removed from the browser). We do not use advertising or tracking cookies.

How we use it

Only to provide and improve the Service: authenticate you, save your progress, show your dashboard, see which lessons are used, and fix errors. We don't sell your data.

While you have a streak going, other signed-in members can see its length on the leaderboard next to your first name and the initial of your last name. Your email and full name are never shown. You can hide yourself from the leaderboard in Settings at any time.

Your rights

You can edit your profile at any time and permanently delete your account and all associated data from Settings.

Contact

Email eduardotaidsr@gmail.com with any privacy questions.