Privacy policy

Last updated November 3, 2026.

Keen (“we”, “us”) makes a daily Sudoku puzzle habit. This page explains what information we collect, why, and who we share it with.

What we collect

• Account information. Your email address, used to sign you in via a one-time link and, if you connect it, your Google account. We don't collect or store passwords.
• Puzzle activity. Which puzzles you've completed, your streak, and your in-progress board state, so you can pick up where you left off.
• Payment information. If you subscribe or buy a gift, our payment processor, Stripe, handles your card details directly — we never see or store your full card number.
• Gift details. If you send a gift, the recipient's first name and a suggested difficulty, if you choose to provide them.
• Basic usage data. Which pages you visit and which features you use, collected through our analytics provider, so we can tell what's working and fix what isn't.

Who we share it with

We use a small number of service providers to run Keen, each of whom only receives what they need to do their job:

• Supabase stores your account and puzzle data.
• Stripe processes payments and manages subscriptions.
• PostHog provides product analytics and crash reporting. It stores this data in the EU.
• Resend sends account emails and your daily puzzle reminder, if you opt in.
• Vercel hosts the site and provides basic traffic and performance analytics.

We don't sell your personal information, and we don't share it with anyone for their own marketing purposes.

Cookies and session recordings

The first time you visit, we ask whether PostHog may use cookies. If you accept, PostHog stores a cookie on your device so it can recognise your visits, and it records how you use our pages (a session recording) so we can see where something is confusing.

If you say no, PostHog sets no cookies and makes no recordings. We still count visits and pages viewed, using an anonymous identifier that PostHog works out on its own servers rather than storing anything on your device. Keen works the same either way.

We also keep a small record of your answer on your device, so we don't ask again on every visit. Signing in uses a cookie too; that one is needed for your account to work.

Your choices

You can ask us to access, correct, or delete your personal information at any time by emailing hello@keensudoku.com. Deleting your account removes your puzzle history and progress; it doesn't affect payment records Stripe is required to keep for accounting and tax purposes.

Children

Keen is not directed at children, and we don't knowingly collect information from anyone under 16.

Changes to this policy

If we make a material change to how we handle your information, we'll update this page and, where required, let you know directly.

Contact

Questions about this policy: hello@keensudoku.com.