Killer Sudoku Online

Killer Sudoku Online has been posting puzzles for many years; the daily killer had reached number 7,619 on 29 October 2026, and the archive goes back to 2008. Its front page carries five puzzles: the daily killer sudoku, a weekly killer, a daily and a weekly Greater Than sudoku, and a weekly Greater Than killer.

In a killer sudoku the usual rules apply, with 1 to 9 once in every row, column and 3x3 box, but the grid is divided into dotted cages whose cells must add up to the small number shown, with no repeats inside a cage. A Greater Than sudoku instead shows inequality signs between neighbouring cells. The daily puzzles get harder as the week goes on, with Sunday usually hardest, and the weekly ones are tougher still.

The online player lets you enter several candidate values in a cell, mark guesses and sure values, undo, check, ask for a hint and save your progress, and its sum calculator lists the ways to make a cage total. Every puzzle can also be downloaded as a PDF. Solutions to the dailies appear in the archives the next day, where older puzzles are also sorted by difficulty.

It suits sudoku players who enjoy arithmetic and like a classic, no-frills site with printable puzzles.

On a phone the site sends you to a separate player at /iphone/. Tapping a cell there opens a small pop-up keypad with the digits, Shift, Space and arrows to move between keypads. That phone menu also lists a daily regular sudoku, which the desktop front page does not show.