How the cipher decoder works
Paste your message and the decoder tries a range of codes and ciphers on it: Caesar shifts, ROT13, Atbash, Vigenère, binary, hexadecimal, Base64, letter numbers such as 8-5-12-12-15, ASCII codes, Morse code and text written backwards.
Each answer is scored by how much it looks like English, and the results are listed with the most likely first. If an answer looks right, press open tool to see it in the tool for that code, where you can change settings or encode a reply.
If nothing looks right
Some ciphers need a key that cannot be guessed easily. If every answer is nonsense but the message is made of letters, it may be a substitution cipher, where each letter has been swapped for another at random. Try the cryptogram solver, which is built for exactly that.
Messages made of dots and dashes are Morse code, and those made of strange symbols may be pigpen, runes or braille, which have their own translators. A message that is mostly numbers between 1 and 26 is very often a letter-number code.
Short messages are the hardest to identify because there is little text to judge. If you can, paste the whole message rather than one word.
A few quick clues help you spot a code by eye. Only 0s and 1s in groups of eight is binary. The digits 0 to 9 with the letters A to F in pairs is hexadecimal. A long run of letters and digits ending in one or two = signs is very likely Base64.
Questions and answers
Which ciphers can it detect?
Caesar, ROT13, Atbash, Vigenère (on longer messages), binary, hexadecimal, Base64, A1Z26 letter numbers, ASCII codes, Morse code and reversed text.
Can it crack any code?
No. Modern encryption cannot be broken this way, and some classic ciphers need a key. It is designed for puzzles, games and simple codes.
Why is the score low for every answer?
The message may use a cipher with a key, a different language, or be too short. Try the cryptogram solver for letter-swap puzzles.
Is my message sent anywhere?
No. Every check runs in your browser.