Privacy Policy

What the Day (“we”, “us”) is a free web app that helps you learn the Doomsday algorithm. This page explains what data we collect, why, and the choices you have. We try to keep data collection to the minimum needed to run and improve the app.

Information we collect

• Account data. If you sign in with Google, we store your name, email address and profile picture so we can create your account, save your progress and show you on leaderboards.
• Gameplay data. When you play, we store results such as the dates shown, whether your answers were correct and how long they took, so we can track your stats, streaks and leaderboard standing.
• Usage analytics. We collect anonymous and pseudonymous information about how the app is used — pages visited, rounds played, device and browser type — to understand what works and fix problems.

Analytics and cookies

We use the following third-party services, some of which set cookies or similar technologies in your browser:

• PostHog — product analytics, to understand how features are used. Traffic is routed through our own subdomain (t.whattheday.com). See the PostHog privacy policy.
• Vercel Analytics — privacy-friendly traffic measurement. See the Vercel privacy policy.
• Google AdSense — advertising on some pages and at the end of practice runs. Google and its partners use cookies or similar identifiers to serve and measure ads.

Most browsers let you block or delete cookies through their settings. Doing so will not stop you from using the app, though some preferences may not be remembered.

Advertising

Ads appear on some pages of the site and as a short break at the end of a practice run — never mid-round while you’re solving, and never in the main game, the daily challenge or the Arena. In regions that require consent, Google’s consent message asks before any advertising cookies are set, and you can change your choice at any time. If you have supported the site, you can hide ads entirely from the support page.

You can read more in how Google uses information from sites that use its services, and control ad personalization in Google’s ad settings.

How we use your data

We use the data above to operate the app, save and display your progress and leaderboards, understand and improve how the app is used, and keep it secure. We do not sell your personal data.

Your choices

• You can use most of the app without signing in.
• You can control cookies through your browser, and ad personalization through Google’s settings linked above.
• You can request access to or deletion of your account data by contacting us.

Contact

Questions about this policy or your data? Email jesper.kiledal@gmail.com.