The fine print
Cookies
Two cookies we need, two more only if you say yes.
Last updated 26 September 2026
What cookies are
Cookies are small notes a site leaves in your browser. Local and session storage are the same idea, but they are never sent with a request: they stay on your device.
Cookies we use
Essential cookies are always on: without them the page would flash the wrong colours and ask for your choice on every visit. Analytics cookies are set only after you accept them.
| Name | Purpose | Type | Lifetime |
|---|---|---|---|
theme | Remembers day or night. | Essential | 1 year |
sleuth_session | Keeps you signed in, if you sign in. | Essential | 30 days, renewed while you use the site |
sleuth_oauth_state | Checks that a Google sign-in is the one you started. | Essential | 10 minutes |
sleuth_oauth_verifier | Proves the Google sign-in to Google (PKCE). | Essential | 10 minutes |
sleuth_return_to | Returns you to the page you signed in from. | Essential | 10 minutes |
cf_consent | Remembers your cookie choice. Set by Cloudflare Zaraz. | Essential | Set by Cloudflare Zaraz |
_ga | Google Analytics: a random visitor id, so a return visit counts as the same visitor. | Analytics, only with your consent | 2 years |
_ga_TE4V82X4RD | Google Analytics: keeps track of the current visit (session state). | Analytics, only with your consent | 2 years |
Browser storage
Your saved progress and settings live in your browser. They never leave your device and we never see them. Clearing your browsing data removes them. The one exception is a rating you choose to give: it reaches us with a random browser ID.
| Key | Purpose | Where | Lifetime |
|---|---|---|---|
sleuth:progress:… | Your saved progress on each case: your entries, undo history and solving time. | Local storage | Until you clear it (we keep your latest 100 cases) |
sleuth:progress:index | The list of cases you have saved progress on. | Local storage | Until you clear it |
sleuth:browser-id | A random ID for this browser, made when you first rate a case, so each case keeps one rating from you. It is sent with your rating and identifies nothing else. | Local storage | Until you clear it |
sleuth:settings | Your player settings, such as conflict checking. | Local storage | Until you clear it |
theme | Day or night, the same choice as the cookie. | Local storage | Until you clear it |
sleuth.analytics.… | Short notes so an event such as “started a case” is counted once. | Session storage | Until you close the tab |
Your choice
You can change your mind at any time. Say no and Google Analytics sets no cookies and collects nothing.
You can also block or delete cookies in your browser settings. The site still works, but it forgets day or night and your cookie choice.
Videos
Video pages show a still picture until you press play. Pressing play loads YouTube’s player from its privacy-enhanced domain (youtube-nocookie.com), which may then store data in your browser under YouTube’s own policy. Until then the only thing your browser fetches from YouTube is that picture, which sets no cookies.
More
What the analytics collect is on Privacy. Questions? Write to privacy@sudoku-sleuth.com.
