Free classic sudoku online
The sudokus that need no extra rule. Suds is the 9x9. Sixes is the 6x6 you finish in two minutes. Diag adds the two diagonals as houses and changes nothing else. Whittle is the same reasoning from the other end: the grid arrives solved and you take clues out for as long as it still has one answer.
Every row, every column and every box holds each digit exactly once, and every Mind Loft board falls to logic alone: singles first, then pairs and locked candidates as the week goes on. Diag adds two more houses, the diagonals. Whittle turns the question around, and the skill is knowing which clue is doing the work.
No. Two independent solvers check every bank before it goes live.
All four, every day, no account required.