K.O. Sudoku - Sudoku Solver

Various types sudoku puzzles, answers, step-by-step explanations, allow take photo to input.
It supports 4/6/8/9/12/16 grid sudoku, jigsaw sudoku, killer sudoku, kendoku, samurai sudoku, flower sudoku, windmill sudoku, gattai sudoku, butterfly sudoku, cross sudoku, twodoku, triple doku, sohei sudoku, odd/even sudoku, compdoku, consecutive sudoku, non-consecutive sudoku, touchless sudoku, anti-knight sudoku, 3D sudoku, balanced sudoku, diagonal sudoku, percent sudoku, window sudoku, asterisk sudoku, girandola sudoku, center dot sudoku, offset sudoku, etc.
There are also technique tutorials and a rich online sudoku store.
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K.O. mode: Provide the solution directly.
Help mode: Provide step-by-step explanations.
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Sudoku Rules: Fill in the 9x9 grid with numbers 1~9 such that each row, column, and 3x3 box contains each number exactly once.
Diagonal Sudoku (X Sudoku): Adds to standard rules by requiring uniqueness of digits in two major diagonals.
Windoku: Adds to standard rules by requiring uniqueness of digits in four extra 3x3 regions.
Samurai Sudoku: Formed by overlaying five 9x9 standard Sudoku grids, positioned at four corners and the center. The objective is to fill the grid with numbers 1~9, satisfying the standard Sudoku rules in each of the five independent regions.
Killer Sudoku: Builds upon the standard Sudoku rules with an additional twist of killer cages (as indicated by dashed lines in the diagram), where the number on the dashed line signifies the sum of the digits within the corresponding cage, and the digits within the cage must be unique.
Kendoku (Newdoku/Calcudoku/Mathdoku): Composed of an NxN grid, which is divided into multiple groups by thick lines. Fill in the numbers 1~N, ensuring that no digit is repeated in each row or column. Additionally, the number and arithmetic symbol (+-×÷) located at the top left of each group represent the answer obtained by performing the specified operation on the digits within that group. If no operator is specified, it means this group can use any of the above operators.
Jigsaw Sudoku: Consists of irregularly shaped, concave and convex boxes arranged within a 9x9 grid. The objective is to fill the grid with numbers 1~9 such that each row, column, and irregularly shaped box contains no repeating digits.
Odd / Even Sudoku: An extension of standard Sudoku rules, incorporates additional circles and squares. Cells with circles must contain odd digits, cells with squares must contain even digits.
Compdoku: An extension of standard Sudoku rules, adds symbols such as great than, and the numbers must satisfy the corresponding size relationships.
Consecutive Sudoku: Adds barriers between grids based on the standard Sudoku rules, with the difference in numbers between grids on both sides of a barrier being 1, and the difference between two grids without barriers definitely not being 1.
Non-consecutive Sudoku: An extension of standard Sudoku rules, requires that the difference between the numbers in adjacent cells is not 1.
Touchless Sudoku: An extension of standard Sudoku rules, requires that each number cannot be the same as its eight adjacent cells.
Anti-Knight Sudoku: An extension of standard Sudoku rules, requires all cells at a chess knight move (at a distance of 2 by 1) must hold different numbers.
Balance Sudoku: Extending standard Sudoku rules by incorporating red balance in the grid, where the sum of the digits on either side of the balance must be equal.
3D Sudoku: Constructed by stacking 27 individual 3x3 boxes in a three-dimensional grid, intersected by 6 colored lines (red, orange, yellow, green, blue, purple). The goal is to fill the grid with numbers 1~9, ensuring that each 3x3 box, as well as the 9 cells along each colored line, contain unique, non-repeating digits.