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Privacy policy

This covers the S2 website (s2.tuanhuydev.com) and the S2 One Question browser extension. S2 is a personal project by Tuan Huy. It does not sell, rent or share your data, and it shows no ads.

What S2 stores

  • Without an account: your lesson progress stays in your browser (local storage). Nothing about it is sent to S2.
  • With a Google or GitHub sign-in: your name, email address and avatar from that provider, your finished lessons, the questions you answered (which question, right or wrong, and when) and your settings. Sign-in goes through Google or GitHub. S2 never sees your password. If both accounts use the same verified email address, they open the same S2 account.
  • Usage statistics: the site uses Vercel Web Analytics and Speed Insights, which count page views and loading speed without cookies and without following you across sites.

What the extension does

The extension asks one S2 question before it lets you open the sites you chose to block. To do that it keeps on your device, in the browser's extension storage: the list of blocked sites, how long a correct answer unlocks them, and, when you are signed out, your recent answers for today's count and streak.

  • It runs only on the sites you block, and only to show the question. It does not read the content of any page, and it does not collect or send your browsing history.
  • It asks for access to a site only when you add that site to your list, and you can remove it any time.
  • When you are signed in, it sends your answers and settings to s2.tuanhuydev.com so they follow your account. Signed out, nothing leaves your device except the request for a question.

Who can see it

Your data is stored with Supabase (database and sign-in) and the site runs on Vercel. They process it for S2 only. Nobody else receives it, and it is not used for advertising or sold.

Your choices

Changes

If this policy changes, the new version replaces this page. Last updated: 15 October 2026.