Can you crack this famous unsolved cipher, created by the Zodiac Killer over 40 years ago? Try it! Click a cipher symbol, then type the letter you want to substitute. I'll show you common words and statistics. Go to for more info.
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Randomize | Reset | Toggle stats | Switch to 408 cipher | Switch to 340 cipher | Flip horizontally | Flip vertically | Rotate left | Rotate right | Find repeated sequences | Dump n-grams (all) | Dump n-grams (repeats only) | Dump alphabet stats | CryptoScope (NEW!) | Zodiac Typewriter (NEW!) |

Technical caveat: I am assuming this is a simple monoalphabetic homophonic substitution cipher, and not something much harder like a transposition cipher or a polyalphabetic substitution cipher. The only reason I am assuming this is because the first 3-part cipher Zodiac sent to the newspaper was solved using homophonic substitution with a single alphabet (to see this, click the "Switch to 408 cipher" link above, and click the decoder named "The correct one").

Click here to view a high-resolution image of the 340 cipher.

Click here to read the Zodiac Ciphers wiki, a new repository of information related to the Zodiac ciphers.

Update History | CryptoScope | Old version of webtoy | zkdecrypto cipher-cracking software | Email me at doranchak at gmail dot com if you find anything interesting or have any comments/suggestions! |

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