Cookie Policy
Last updated: 11 August 2026
This policy explains the cookies and similar browser storage Sudoku Player UK ("SPUK") uses. We use one set of essential sign-in cookies, browser local storage to save your puzzle in progress, and — only if you say yes — Google Analytics. We don't use advertising or retargeting cookies of any kind, and there are no ads on SPUK.
Strictly necessary cookies
These are set automatically when you sign in, by our authentication provider, Supabase. They're required for the site to know you're signed in — without them, you'd be signed out on every page load. Because they're strictly necessary for a feature you've requested (staying signed in), UK/EU cookie law doesn't require us to ask for consent to set them.
| Name pattern | Purpose | Duration |
|---|---|---|
| sb-*-auth-token | Keeps you signed in between visits | Until you sign out, or it expires |
Analytics cookies (optional — only with your consent)
We use Google Analytics to understand how many people visit SPUK and how they use it (e.g. which pages are popular), so we can improve the site. This sets cookies that are not strictly necessary, so — unlike the sign-in cookies above — UK/EU law requires us to ask first. When you first visit, a banner asks you to Accept or Reject; we only load Google Analytics, and only set these cookies, if you click Accept. Rejecting (or not responding) means they're never set.
| Name pattern | Purpose | Duration |
|---|---|---|
| _ga | Distinguishes unique visitors | Up to 2 years |
| _ga_<container-id> | Persists session state for Google Analytics (GA4) | Up to 2 years |
You can change your mind at any time — click below to reopen the consent banner:
Local storage
Separately from cookies, we use your browser's local storage (data saved on your device, not sent to us on every request the way cookies are) for:
| Key | Purpose |
|---|---|
| spuk:game-state | Saves your in-progress puzzle (the grid, pencil marks, timer, and difficulty) so it's still there if you close the tab or come back later. Used for both guests and signed-in users. |
| spuk_guest_banner_dismissed | Remembers that you've dismissed the "you're playing as a guest" banner, so it doesn't keep reappearing. |
| spuk_cookie_consent | Remembers your Accept/Reject choice for analytics cookies, so we don't ask on every visit. |
What we don't use
We don't use advertising, retargeting, or third-party tracking cookies, and we don't sell or share analytics data. There are no ads on SPUK. Google Analytics is the only non-essential service we use, and only with consent (above).
Controlling cookies and local storage
Use the consent banner (or the "Cookie Preferences" link above / in the footer) to accept or reject analytics cookies at any time. For the strictly-necessary sign-in cookies and local storage, you can still clear them through your browser's settings — note that doing so will sign you out and/or lose any in-progress puzzle that hasn't been completed. Rejecting or clearing analytics cookies doesn't retroactively delete cookies already set by a prior Accept — clear them manually via your browser if you want a hard reset.
Changes to this policy
If we ever add new cookies or storage, we'll update this page and the "Last updated" date above.
Contact
Questions about this policy? Email us at jim@sudokuplayer.co.uk, or get in touch via our Feedback page.