Sudoku Solver for Android

Welcome to the project page for the SudokuWiki Solver, an App for Android.

Update 7th June 2025


Update 5th June 2025


Update 4th June 2025: Latest version now in review and should be rolled out to all devices very shortly. A complete refresh of the solver code as I've made numerous efficiency and optimization changes in the last fifteen months, plus some new strategies. Also the hint mode should be easier to work with as it updates the board instantly, without having to step back and forth. Any new bugs, please let me know.

Unfortunately I loose about 5% of devices with this release as the minimum Android version I can support is now Android 5 (Lollipop, API 21) so anyone still on 4 (KitKat), sorry. But that is more than ten years old. This is required to support Android 15 (API level 35).

Update 26th of March 2024: So it looks like my release of version 1.84 in October 2023 never made it to the Google Play Store - some irrelevant regulatory tick boxes needed to be ticked and I didn't hear about them. So everyone was still on v1.82 which was for a pretty old version of Android and now I'm getting feedback saying the app isn't compatible. Today I have released 1.85 but it is "in review" for up to seven days. Contains all the new stuff from the last six months. Hopefully fix all the problems and the reviews that say it is 'abandonware'. Certainly isn't!

Latest version 1.89 - 7th of June 2025 Released £3.49 - Your local sales tax is included in the price. Your local currency will apply in your locale.

Search for "SudokuWiki"

Change Log

Version 1.89, 7th June 2025

• Grader will now ignore strategies that have been deselected but take the score with a pinch of salt as you can only compare it to puzzles with the same strategies deselected.
• Bug fixes

Version 1.88, 5th June 2025

• Updated to Android 15 (API level 35)
• All example puzzles have been replaced as the original ones were not all occurring due to changes in the solver.
• Added Chute Remote Pairs
• Added Twinned XY-Chains
• Expanded 'hint mode' and changing hint mode immediately redraws the board.
• Internally much code refactored and improved.
• Refreshed all documentation. 'Load Example' now works with packed strings where present in the documentation.

Version 1.85, 26th March 2024

• Updated to Android 14 (API level 34)
• Added Rectangle Elimination and removed Empty Rectangles
• Fixed Unique Rectangle Type 3B to also use the third cand in triple
• Added Extended Unique Rectangle Type 2
• Refreshed all documentation

Version 1.84, 18nd September 2023

• Updated to Android 13 (API level 33)
• Added Extended Unique Reactangle Type 4
• Expanded Hidden Unique Rectangle Type 1 to get more eliminations if symmetrical
• Refreshed all documentation

Version 1.83, 22nd April 2022

• Added 'Fireworks 'bent set'
• Corrected http to https on export links
• Changed export to email to general 'share' intent

Version 1.81, 4th March 2021

• Added 'Type 5 Unique Rectangles

Version 1.80, 8th January 2021

• Added 'Exotic Links' to AIC chains

Version 1.78, 20th March 2020

• Updates to the core engine sudoku strategies to version 2.19
• New WXYZ algorithm
• Added SK Loops
• Added URs to Chains
• Refresh of the documentation

Version 1.77, 26th November 2017

• Updates to the core engine sudoku strategies to version 2.12
• Additional captures in Nice Loop strategies
• Refresh of the documentation
• Checked and replaced example puzzles in case outcomes had changed

See all the update notes at the end of the development page. Approved on Google Play (World-wide) Approved on Amazon.com (seems to be just USA at the moment) Please leave a review. I'd love to hear your feedback. Any issues email me directly - bugs are easy to fix. The build log and progress update on the upgrade version has been moved to a new page.

Sudoku Solver and Grader This App contains the full 9x9 Sudoku Solver as seen on this website. This includes the Grading feature and Solution Counter. 364 Practice Puzzles Expanded Samples List: now organized into groups that focus on a specific strategy. Smartphone to Tablet Four different layouts have been designed to match the many different Android screen sizes and pixel densities from Smartphones (minimum 480x800) to tablets (1280x800). Strategy Guides Included are all the strategy documentation found on this site and each example can be loaded into the solver at a click. Puzzle Feed The Daily and Weekly puzzles on this site are now automatically downloaded into the App! Customisation The solver board can be set to several color schemes including high contrast colors. Favourites Keep track of the puzzles you solve with an almost limitless list entry - each nameable. Hints New to our solver - Instead of just "Take Step" use "Hint" to give you the strategy to look for without revealing the whole answer. Undo/Redo Better than the website with real 'state' saving - quit, resume any time and a start to end 'back' and 'forward' buttons.

View more Screen Shots Access to the main features from the home page Note: Screen shots have been taken from a 480x800 device and shrunk by half. Other devices may have higher screen resolutions and marginally different layouts.

You feedback will be most welcome. If you have an idea for a new feature or improvement, don't be shy. Often these can be implemented very quickly. Bugs and other issues most gratefully received.

• I am not 100% certain the different layouts groups I've designed will perfectly match all screen densities and resolutions. If you think the solver page or main page looks a little odd - either clipping or too much padding - please let me know. I can add more layouts. Please include the screen information found at the end of the Preferences screen.


• Practice Puzzles - puzzles that contain specific strategies


• A future upgrade will contain the Sudoku X and Jigsaw Sudoku puzzles - complete step-by-step solvers including grading and solution count. There will be an editor for entering Jigsaw patterns not found on this site or in my puzzles.


• I will explore Camera Capture. This is the only major feature present in the iPhone version that's not in this app. Something I'd like to do but it will require a lot of research.


• The 'hint' system could use some more work. I prefer the three levels of hints in the iPhone version and I'll be working towards this in later versions. Currently the hint system reveals the strategy used and colors some cells and candidates, but not the eliminations. This can be too much for some strategies and too little for others. Two levels of hints are now in the App


• The app has the ability to call and email program with a link to the website solver and the current puzzle. I'd like to do more and add some kind of Facebook connectivity.