Expert Killer Sudoku Online
Free 9×9 killer puzzles at the hardest tier — extreme technique required.
Generating Killer puzzle…
Expert layouts can take a few seconds to verify.
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Last 7 DaysExpert Killer Sudoku is the hardest tier we generate. Cages average 3-4 cells, so cage-combination enumeration alone rarely cracks a puzzle — you'll need X-wings, swordfish, naked triples, and patient innies-and-outies arithmetic across multiple boxes simultaneously. Sessions take real time; even confident solvers spend thirty to sixty minutes here. Sudoku247's Killer generator runs every Expert puzzle through a cage-aware constraint solver and only ships layouts with a single unique solution, so when you finish, the answer is correct by construction. Show Candidates fills every cell with the digits that satisfy row, column, box, AND cage rules — invaluable on Expert for spotting which cage-combinations are actually achievable given the surrounding state.