Strategies for Popular Number Puzzles

Sudoku Solver for Android

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

Update 26th of March: 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!

Next version 1.85 - 26th of March 2024
Get it on Google Play
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Change Log

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
Version 1.80, 8th January 2021
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 (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!
The solver board can be set to several color schemes including high contrast colors.
Keep track of the puzzles you solve with an almost limitless list entry - each nameable.
New to our solver - Instead of just "Take Step" use "Hint" to give you the strategy to look for without revealing the whole answer.
Better than the website with real 'state' saving - quit, resume any time and a start to end 'back' and 'forward' buttons.
Screen Shot 1
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.

Feedback and Wish-List

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.



... by: Jonathon Schmidt

Friday 12-Jan-2024
I’d enjoy using your app, but I’m finding its set up for android and I have an Apple product. Any suggestions other then buying into android?

... by: Chris

Monday 26-Sep-2022
The 'board' (grid) could be bigger - there is a good deal of wasted space on left/right sides. The info on the 'preferences' screen is:
Screen size: NORMAL 2047 x 1080
densityDPI=420 density = 2.625 scaledDensity=2.625
xdpi=391.885, dpi=391.29675. My phone is Samsung S10+ (big!) and has a 'large font' setting somewhere.

I discovered that I can change cell and number colors, and that has helped with 'high contrast' issues. But the highlights of candidates in cells prior to removal is poor - it's basically a 'purple' highlight on a dark number, so all you see is a blob'. You can infer the number from it's position of course.

I feel like the 'take step' does 'too much' in one go, sometimes. If I see a candidate that can be removed, I tap in the cell and then tap the number to remove it. Assume this is the last candidate. I hit 'take step' and I want that number to be placed in the cell as a solution, and then the next 'take step' I want to evaluate ONLY the impact of that one solved cell, but it seems like the solver also solves any other cells at the same time, which is doing more than I want it to do. Hard to explain; I can explain better in email.

Version is shown as v2.27 sw360.

... by: GeorgeSt/GeorgeSt

Sunday 16-Jan-2022
Hi. I just I found your website. It's amazing. To learn python, I wrote such a program (there are 8 algorithms in total that I needed). I tried the first Sudoku and immediately my solution differs from yours. And I can't understand yours. LINK

[5,6,0,0,2,0,0,0,0], yours is 1 at D6, why?
[7,0,0,0,0,0,0,0,0], my is 1 at F2
Andrew Stuart writes:
My solver finds both D6 and F2
SINGLE: D6 set to 1, unique in Row
SINGLE: F2 set to 1, unique in Box - [Del]
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... by: Davek

Thursday 23-Sep-2021
Love the solver and explanations. Thanks

... by: Wayne Wilkinson

Thursday 3-Sep-2020
I really love the solver on the web page. I am an amateur c programmer and have been working on a sudoku solver using non-brute-force methods. Can you help me find algorithms for some of the advanced techniques? I have already implemented x-cycles using depth first tree search. Thank you very much.

... by: mohammad

Tuesday 16-Aug-2016
Hello. I am from Iran and I can't purchase sudoku solver app please send this application to my email. I really need it and like it. Thank you very much. Buy!!

... by: Felstarr

Thursday 5-Mar-2015
Hi! I just purchased your app on Google Play for my LG G3. Unfortunately, I cannot read the numbers in the actual game grids -- the type is too light and too small. Anything I can do to enlarge and/or bold the font?
Andrew Stuart writes:
Can you go to the preferences screen, scroll to the bottom and tell me what the specificatiions are. For all devices I have tested I have tried to maximise the space used and make the numbers as large as possible. For small devices this might still not be enough. Do you know how to take a screen shot with your device? That would help me see if I can improve it - [Del]
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... by: Janet

Tuesday 19-Aug-2014
It would be great if this were available for ipads.

... by: JPF Naperville, IL

Monday 14-Jul-2014
Why are their no extreme puzzles on the daily list of puzzles? also
no unsolvalbles?
Andrew Stuart writes:
The weekly unsolvable IS in the pull down of daily puzzles, but only changes once per week, obviously. I dont have an extreme in the Daily Puzzles set currently, they are not for normal newspaper publication. But I might consider including one in a future update. - [Del]
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... by: Mike

Tuesday 24-Jun-2014
Hi Andrew,

I find your Sudoku solver extremely useful, thank you for creating it. Does the Android app require internet access to function? Especially the solution count function? I would like to use it on an Android ipad but I don't usually have internet access.

Andrew Stuart writes:
No, the App only requires internet access to download the Daily Puzzles, which are entirely optional. All solving is done inside the App. - [Del]
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... by: Joerg

Tuesday 25-Mar-2014
I purchased the app yesterday and I am not able to get a new puzzle into the solver (on Sunday 24-Mar-2013 alain maronani wrote the same), neither from main menu "New Puzzle" nor the solver "Edit Clues". The only way to leave is the original phone back button and then the solver contains the old puzzle. But "Daily Puzzles" work.
It's a SAMSUNG Galaxy GT-S5830i, Android version 2.3.6., resolution: NORMAL 480 x 320, densityDpi= 160, density= scaleDensity= 1.0 xdpi= dpi= 162.56
Your online solver is great and I hope I can use the app, too.

Thanks for any help

... by: Alan West

Tuesday 17-Sep-2013
This is a good app and I like the hinting system...

For 'accessibility' the app could do with a fontsize +/- for candidates/solutions. On my Nexus 7 tablet (V2) the fontsize for the candidates is too small to read comfortably and even on the Samsung S3 phone, where it is better, I'd still like the option.

Also (but this could be my lack of understanding), for those of us who like to get as far as possible without help, I think it should be a lot easier to manually enter either solved numbers AND (pencil) candidates without mode switching - most apps offer two lines of number keys ('large' and 'small') which is a lot more intuitive!!

Andrew Stuart writes:
I agree, more can be done with font sizes. The problem is that there are so many screen sizes it's a challenge to make it work on all of them. I'll look into a dynamic small/large control.

I'll also look at the control for small/large numbers again. It has been tweaked several times but I am leaning towards a toggle button now.
- [Del]
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... by: Piotr

Saturday 17-Aug-2013
On a SONY S Tablet running Android 4.0.3 the application starts upside down.

... by: Jose Vega

Thursday 16-May-2013

I just downloaded sudokuwiki solver for android. I think I discover a bug or funcionality (?)

Go to the Strategy docs and pickup whatever section. Navagate through it and then change the device orientation. The document will go back to the beginning of that section.

It's frustrating that the candidates popup appears sometimes hiding the area of influence of the chosen cell.

Would be nice if the application could read a sudoku printed using the camera of the device.

Mi Phone is a samsung galaxy II with android 4.1.2

Thanks for the app !
Andrew Stuart writes:
Thanks for the helpful feedback.

I'm not sure what to do about the docs resetting to the top when re-orientated. It is a web page embedded in a browser object. When reorientation occurs all objects, even app forms and screens, are thrown away and redrawn. There is code in place to restore the contents so its seamless to the user, but it doesn’t extend to the position the user was last on a web page. But I'll do some research, you never know.

> It's frustrating that the candidates popup appears sometimes hiding the area of influence of the chosen cell.

That shouldn't occur and I've tested it on several sized devices - I also have a Samsung galaxy II. Can you go to the preferences screen and tell me what is written at the bottom? It will be something about screen sizes etc. That will help me identify what to look for. Also, if you are up to it, a screen shot of the overlapping popup would be awesome! (
I think you can email from the phone picture library.
I am working on the Camera feature, certainly the last major missing item. - [Del]
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... by: AStanley

Saturday 30-Mar-2013
I would love to have the solver available for my Nook tablet from Barnes & Noble. As of now the only apps I can have are from them. HELP!!!

... by: Marcel

Saturday 16-Feb-2013
I now got the app from Google play. So far it looks good, but there is one minor annoyance:
The app only allows portrait orientation. However I have an Asus transformer, and with keyboard attached, it is automatically in landscape mode and so I can't use the app when I have the keyboard attached.
It would nice to have the possibility to run the app in portrait mode, even without new screen layout. E.g. I could live with the app wasting screen space on a tablet because of the wrong orientation.
Andrew Stuart writes:
I will do that. I hadn't appreciated the device being used in that way, I assumed each orientation was equally optional.
Edit: Now in the current version

Thanks for the feedback!
- [Del]
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... by: Ludek Frybort

Monday 11-Feb-2013
I'm happy to see the solver published on Google play!
Now I'm eagerly waiting for and looking forward to an update with Camera Capture included. Until then I'm not buying the app as I have no use for an Android solver without capture. As soon as it's included, I'll wait no more to buy it even if it costs substantially more than the current price then. I'm sure it'll be worth it.
Andrew Stuart writes:
I will be researching Camera stuff very soon. I know Oliver had a lot of difficulty with the iPhone version and not everyone is reporting good success with the capture. But we will see. - [Del]
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... by: slowofmind

Saturday 9-Feb-2013
It isn't worldwide.
I live in 'Trinidad & Tobago' and also cannot order from Amazon App Store.

However I downloaded the solver from Google Play this morning (about 2 am),
and got it. Will look at it later. I know it will be excellent!

Victor G.

... by: Marcel

Sunday 3-Feb-2013
Because of geographical reestrictions, I cannot purchase this app. :(
(My Amazon account is registered for Luxembourg)
Andrew Stuart writes:
I am looking at why this is. Peter, below, in South Africa also says the same. It should be world-wide apart from Japan. I'll post a message when I know more about it - [Del]
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... by: Peter Cherry

Monday 21-Jan-2013
Hi Andrew,

How's the Android Solver coming on?
I can't wait to purchase it!
I've effectively learn't Sudoku using your web solver and I just love it.

Kind regards,
Peter Cherry from South Africa

... by: vikviper

Sunday 2-Dec-2012
So what's going on for the android version?
Andrew Stuart writes:
I've started! And its not going to take a year, promise! - [Del]
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... by: RoC1909

Thursday 9-Aug-2012
Any word on the Android version or has it turned into vaporware? Kind of curious because I would really like the app.
Andrew Stuart writes:
I want the Android app too. Now the plan is for me to go on an android developer course. - [Del]
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... by: Roc1909

Wednesday 9-May-2012
Frankly, you could have charged more and I would most likely have no problem with buying it. While I don't have the ability to use the program yet (I am an Android person), the list of features alone makes this something that would warrant a higher cost.
Andrew Stuart writes:
Thanks for the endorsement and the comment. I think it’s a very difficult balance between perception of value and the giveaway prices some apps are set up. I was actually a little worried it was too high. You never know how many decide not to buy. Looking forward to the Android version as well - [Del]
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... by: RoC1909

Wednesday 9-May-2012
*Patiently waiting for an Android version


... by: Don

Wednesday 8-Feb-2012
I would like to beta test the Android version. I have several sudoku apps but none of them really do the job.

... by: Todd

Friday 9-Dec-2011
I would love to beta test your Sudoku solver for android.

... by: KV Rajah

Monday 21-Nov-2011
If u can do a solver for Android like, please inform. The only drawback I find in is that it does not allow you to create a sudoku from print like Simple Sudoku.
Article created on 15-December-2012. Views: 119243
This page was last modified on 26-March-2024.
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