OneTaskBy Tim King · Updated
Cryptogram Solver
Substitution Cipher Decoder With the Letter Key and Known Letters
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How the Cryptogram Solver works
This cryptogram solver cracks letter-swap puzzles such as newspaper cryptograms and cryptoquotes. Paste the coded message and it finds dictionary words that fit every coded word at once, then shows the most likely reading, a few alternatives and the letter key.
How the cryptogram solver works
Every coded word has a pattern of repeated letters. XQX can only be a word with the same first and last letter, such as DID or EYE. The solver lists every dictionary word with the right pattern for each coded word, then fits them together so that each code letter always means the same plain letter and no two code letters mean the same one. Readings made from common words score highest.
Steering it with known letters
Short messages can fit several readings. If the top answer is nearly right, add the letters you are sure of, such as Q=E, X=T, in the known letters box. The code letter goes first. The solver then only considers readings that agree, which usually settles the rest.
Names and rare words
Names and unusual words are not in the dictionary, so the solver leaves them out of the search and shows their letters as ? where nothing else fixes them. They are listed in the note above the results.
FAQ
What kind of codes can it solve?
Simple substitution ciphers, where each letter is always replaced by the same other letter. That covers newspaper cryptograms, cryptoquotes, Caesar shifts and Atbash. It cannot solve codes that change the swap as they go, such as the Vigenère cipher.
Why is the top answer slightly wrong?
Two readings can fit the letter patterns equally well, such as LET and GET. The solver ranks by how common the words are, which is right most of the time but not always. Look at the other readings, or give it one letter you are sure of.
Does the punctuation matter?
Spaces and apostrophes matter a lot, because they fix word lengths and patterns like IT'S. Keep them as printed. Commas, full stops and other punctuation are kept in the output but do not affect the search.
See also: all Puzzle Solvers tools, Scrabble & Board Games, Anagrams & Rhymes, Puzzle Makers.
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