Last updated 23 September 2026

Cordwood Sudoku privacy

This policy covers the Cordwood Sudoku app for Android (com.cordwoodlabs.sudoku), published by Cordwood Labs LLC. It is short for an unusual reason: the app has no permission to use the network, so there is no mechanism by which it could send us anything.

What the app collects

Nothing. There are no accounts, no sign-in, no analytics, no advertising, no crash reporting, and no tracking of any kind. We do not know who you are, that you installed the app, or that you ever opened it.

You do not have to take our word for it. An Android app can only reach the internet if it declares the INTERNET permission, and this one does not. You can check that yourself: the Play listing shows every permission an app requests before you install it. Cordwood Sudoku asks for two: VIBRATE, for the short tick when a key is pressed, and com.android.vending.BILLING, which lets it ask the Play Store app whether you have bought the unlock.

The copy you install from Google Play has a third, which Google adds to it, not us: com.android.vending.CHECK_LICENSE. It lets the app ask the Play Store app whether this copy came from Google Play, so that a copy from somewhere else can point you to the real one. Like the unlock check, it is a question to the Play Store app on your phone, not a connection to the internet. None of the three can carry data to us, and we have no server for it to arrive at.

What the app stores on your phone

The game keeps your progress on the device so you can put it down and come back. That is all local storage on your own phone, and it holds:

• the puzzles you have started or finished, the digits and pencil marks you have entered, how long you have spent, how many hints you used, and the undo history for the puzzle you are on;
• your settings — difficulty band, variant, light or dark theme, which assists you have switched on, whether the key tick is on, your device's language, and which release you have already been shown;
• whether the unlock has been bought, which is stored as nothing more than a true-or-false and the time of the last answer from the store. No order number, no receipt, and no payment details are kept.

None of this is sent anywhere by the app, and none of it is visible to us. Deleting the app removes all of it. You can also clear it without uninstalling, from Settings › Apps › Cordwood Sudoku › Storage.

Android's own backup

One thing does leave the phone, and it is worth being precise about because it is not the app doing it. Android has a backup feature of its own, which copies app data into your Google Drive so that a new phone can restore it. Cordwood Sudoku allows this deliberately: if you change phones, your solves should come with you, and there is no copy of them on our side to restore from instead. If you have device backup switched on, your saved progress and settings are included.

That copy belongs to you, sits in your Google account under Google's terms, is encrypted, and does not count against your Drive storage. We have no access to it whatsoever — it is not sent to us, and we could not read it if it were. You can turn it off for every app in your device's backup settings.

If you buy the unlock

The paid unlock is sold through Google Play, and Google handles the entire transaction. Your payment details go to Google, never to us — we never see a card number, a billing address, or your name. The app asks the Play Store app one question, "has this person bought it", and stores the yes or no described above. What Google does with the purchase is covered by Google's own privacy policy and the Play terms you agreed to with them.

We do receive sales information from Google in aggregate, as any developer does: how many copies sold, in which countries, and the money. That reporting does not identify individual buyers to us.

If you email us

Mail to support@cordwoodlabs.com is forwarded by Cloudflare Email Routing into a Google mailbox we control. We keep your message and our reply so we can follow up, and we use your address only to answer you. We do not add you to any mailing list. Ask us to delete the correspondence and we will.

Children

Cordwood Sudoku is a general-audience puzzle game. It is not directed at children, and it does not knowingly collect information from anyone, of any age, because it does not collect information at all.

Deleting your data

There is nothing held by us to delete, so there is no request to make and no form to fill in. Everything the app saves is on your own device and goes when the app does. If you have used Android's backup, deleting that copy is done through your Google account.

Changes

If this policy changes, the date at the top of this page changes with it. There is no archive of previous versions; if you need one, ask and we will send you what we have.

This page

This is a page on our website, and visiting it is covered by the cordwoodlabs.com privacy policy — briefly, our host sees an ordinary web request and the typefaces come from Google Fonts. The app itself does neither of those things.

Contact

Questions about privacy go to support@cordwoodlabs.com, which reaches a person and not a queue. Cordwood Labs LLC is a limited liability company registered in New Hampshire, United States.