atkuzu Daily

Privacy policy

Last updated 2026-09-09.

atkuzu is a Takuzu puzzle client for the AT Protocol. Its guiding idea is that your data lives in your own Personal Data Server (PDS), not on atkuzu's servers, atkuzu is just the client. This page explains what that means in practice.

Data stored on your PDS

If you sign in with your AT Protocol handle, your puzzle results, statistics, and display preferences (such as your chosen board theme) are written as records on your own PDS, under your own account. atkuzu reads and writes these records through the OAuth permissions you grant at login. You control that data directly through your PDS, independently of atkuzu.

Data stored on atkuzu's server

To keep you signed in, atkuzu's server stores:

  • A single session cookie, a random token, marked http-only and secure, sent only over HTTPS in production.
  • A matching session record (your DID, handle, and the session's creation and expiry dates) in atkuzu's own database, so the cookie can be validated.
  • Temporary OAuth state (keys and nonces used during the login handshake), cleared once login completes.

None of this includes a password or email address: sign-in works entirely through your AT Protocol identity and PDS, atkuzu never sees or stores a password.

Server logs

Like most web servers, atkuzu keeps operational logs (timestamps, request errors, and occasionally a DID when diagnosing a failed session). These logs exist for debugging, are not sold, shared with advertisers, or linked to any tracking identifier.

No tracking, no ads

atkuzu does not use analytics scripts, advertising trackers, or third-party sharing of any kind. Nothing here is monetized through your data.

Removing your data

Signing out clears your session cookie and its server-side record. Because your puzzle results, stats, and preferences live on your own PDS rather than on atkuzu's server, you can inspect, export, or delete them at any time using your PDS's own tools, independently of atkuzu.

Questions

If anything here is unclear, open an issue on the issue tracker or reach out via tomplanche.com. This policy may be updated as the project evolves; changes will be reflected on this page.

Login

Sign in with your AT Protocol handle.

How to play

Fill the grid with 0s and 1s so that every row and column follows these rules:

  • No three in a row. The same digit can't appear three times in a row, in either direction.
    011100
  • Balanced rows and columns. Each row and column has the same number of 0s and 1s.
    110101
  • No duplicate lines. No two rows are identical, and no two columns are identical.
    1010
    1010

A cell that breaks a rule turns red as soon as you place it, so you always know where to look.

Controls

  • Click or Space cycles a cell through blank, 0, and 1.
  • ← ↑ ↓ → move focus between cells.
  • Enter submits the puzzle once it's full.
  • Ctrl+Z (Cmd+Z on Mac) undoes a move,
    Ctrl+Shift+Z or Ctrl+Y redoes it.
    Or use the Undo/Redo buttons above the board.

Board theme

How filled cells are drawn on the board, on both /play and /daily.

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