Decoder

consistency solver
search space 2,562,890,625
100%

Play Mastermind wherever you like — on paper, in an app, against a friend. Record each guess here with the key pegs it earned, and Decoder keeps every code that still fits and picks your next guess.

The board

no guesses yet
Next guess
Start here — ask for an opening guess to play.
black — right peg, right slot white — right peg, wrong slot you record these yourself

Pick a slot, then a peg — or type the code as numbers. The numbers are just labels, so match them to your own colours however you like.

Candidate field

every code is still possible
In the pool
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Survival rate
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Codes left, est.
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