Sudoku Assistant

This online Sudoku Assistant app. helps you to solve Sudoku puzzles. It includes a solver and has many features such as note making and display of number candidates. Also, you can enter the given numbers of a puzzle individually or from a puzzle string.

User Guide

User Guide

Number Entry Modes

The mode (entering given numbers, solving, or entering notes) is indicated at the top of the control panel.

Given numbers are displayed in a dark gold color and other numbers in black.

Numbers are entered by first selecting a cell in the grid, then typing a number or clicking on a number button. Any other key or the blank button clears the selected cell.

Initially, the App is in the Entering Givens mode. This is where you set up the grid with the initial numbers of the Sudoku puzzle.

The edit pencil button toggles between Solving mode and Adding notes (candidate numbers).

The edit_square Pencil on paper button toggles between Entering Givens and Solving modes.

Candidate Numbers (Notes)

Small note numbers may be manually added when in Adding notes mode or existing note numbers removed.

The add Plus button fills in the candidate numbers for an empty selected cell or removes these numbers from the cell.

The add_circle Circled Plus button fills in the entire grid with candidate numbers or removes them all.

Checking Your Solution

Clicking the check Tick button cycles between highlighting incorrect/correct numbers (if the option is enabled), revealing the solution, and then back to solving the puzzle. To avoid seeing the solution, only click the Tick button once, then enter a number or select a cell in the grid.

The solution is evaluated when transitioning from entering Given numbers to Solving as long as at least one Given number is present. The first solution found is the one that will be used or just zeros if no valid solution is obtained.


The play_pause Play/Pause button starts or pauses the time counter and next to it is the restart_alt Time Reset button.


The delete Bin button wipes the grid ready to enter a new puzzle. Use with caution since it erases all of your number entries.


Various check boxes are provided to enable/disable certain features such as highlighting, and helpers. So this allows for distractions and helpers to be turned off.

Using Puzzle Strings

A text input box is provided for entering puzzle strings. This can be a quick way to copy a puzzle and Apply it to the grid.

Enter numbers 1..9 or any other key for a blank cell (indicated by a dot). These are mapped from left to right, wrapping to the next row of the grid. You don't need to pad the right side with blanks.

You may also copy and paste a puzzle string into the box.

Puzzle Text Strings

With the numbers entered, click on the Apply button to populate the grid and enter Solving mode.

To capture the Given/Clue numbers of the grid to a puzzle string, click on the edit_square Pencil on paper button when in Solving mode to move into Entering Givens mode and triggering the puzzle string to be built. Then You are able to copy and paste the generated string to save it in a text file on your computer for later re-use.

Clicking the same button after having partially solved the puzzle will copy all the grid numbers to the puzzle text string. So you can save your progress for later i.e. cut and paste it to a text file.

Solving Strategies

Various buttons are provided that evaluate the grid for various Sudoku Solving Strategies from simple to more advanced. Pressing the button highlights any candidate numbers in Green that imply numbers in Red may be eliminated. The buttons blink Red if there are no matches for the particular strategy.

Learn how to solve Sudokus


Some buttons are provided to do tedious tasks such as removing red candidate numbers and converting single candidates to grid number entries.


Cells in the grid may be referenced in your notes or online by 1-9 and A through J with I not being used for clarity. Thus, A1 refers to the top left cell and J9 the bottom right cell. And row J is the bottom row, and column 1 is the leftmost column etc.


It involves a huge amount of time to delevop an App and to provide it online involving some money for the web hosting. But I do it for fun, yet I don’t mind a bit of financial support if you feel inclined (I am actually unemployed but not broke) …

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