Open Sudoku

Open Sudoku is the maintained open-source continuation of Roman Mašek’s Android Sudoku app. It focuses on playing and organising conventional 9×9 puzzles rather than generating endless variants. The installer includes 90 puzzles split across three difficulty levels, so it is useful immediately without a connection.

The whole game works offline. Its manifest declares camera as the only user-facing permission, and that is only for an experimental scanner that remains hidden unless you turn on Experimental Features.

Playing and keeping puzzles

The app groups puzzles into folders and records progress, time and mistakes. You can use different entry modes, ordinary and secondary pencil marks, undo and checkpoints, and optional helpers that highlight conflicts or wrong values. Themes and a custom theme editor change the board’s appearance.

Hints are not limited to revealing a final digit. The hint system can describe a next logical step and the strategy behind it. Mistake checking defaults to the indirect setting, and assistance is configurable; players who want a paper-like solve can change correctness checks and leave hints unused.

Besides the 90 included boards, you can:

• type a puzzle into the grid yourself;
• import supported Sudoku puzzle files obtained with another app;
• export collections for backup or transfer; and
• filter the game list by status, while using folders you create to organise puzzles.

The project’s references to downloading more puzzles do not mean this APK downloads them in the background. It has no internet permission. Obtain a compatible collection through a browser or computer and then open or import the local file.

Experimental camera scanning

Open Sudoku includes a scanner built with OpenCV and TensorFlow Lite for reading a printed grid through the camera. It is explicitly experimental and must first be enabled in Experimental Features. Lighting, perspective, print quality and handwriting can all affect recognition, so verify every clue before solving. Granting camera access is unnecessary if you play included puzzles, enter them manually or import files.

The OpenCV and TensorFlow Lite native components contribute to the APK’s size. Upstream itself limits this build to arm64-v8a with its ABI configuration; a 32-bit ARM or x86 Android device cannot install it even if its Android version is otherwise new enough.

Version and privacy

Version 4.11.3 is a focused maintenance release: its stated change is a crash fix for devices using sixteen-kilobyte memory pages. It does not claim new puzzle types or online play.

The APK asks for no internet permission, contains no advertising or in-app billing code and our scan found no tracker libraries. Puzzle data stays local unless you deliberately export or share a file. Android or a device maker can still back up app data according to system settings; “offline app” is not a promise about the entire operating system.

About this file

• This is F-Droid’s build of 4.11.3, signed with F-Droid’s key. A build from another signing line cannot update it in place.
• The 19.4 MB APK needs Android 8.0 or later and a 64-bit ARM processor. It declares one permission, camera, for the opt-in experimental scanner.
• Our scan found no trackers and no internet permission.
• Open Sudoku is licensed under GPL-3.0 or later. Its OpenCV and TensorFlow Lite scanner components keep their respective open-source licences.

CPU types in this build: arm64-v8a (64-bit ARM, almost every phone since 2017).

Versions currently kept in the F-Droid repository. We host and check only the newest one. Full changelog.