Caesar cipher and other classic ciphers
Encode or decode a message with a classic cipher: Caesar (shift every letter), Vigenère (shift by a keyword) or Atbash (reverse the alphabet).
How it works
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Type your message
Type or paste the text you want to encipher or decipher.
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Choose the method
Caesar (shifting), Vigenère (with a keyword) or Atbash (the alphabet reversed).
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Copy the result
The result appears straight away. Switch direction to make a message readable again.
The three ciphers
- Caesar: every letter moves a fixed number of places in the alphabet. With a shift of 3,
AbecomesD, andMeet at the bridgebecomesPhhw dw wkh eulgjh. A shift of 13 is ROT13. - Vigenère: like Caesar, but the shift changes with each letter, following a keyword. With the key
SECRET, letters are shifted by S, E, C, R, E, T in turn, which defeats simple frequency counting. - Atbash: the alphabet is mirrored, so
AbecomesZ,BbecomesYand so on. There's no key.
Choose Decode to reverse it. Only the letters A–Z change; digits, punctuation, spaces and accented letters stay as they are.
Not real security
These ciphers are centuries old and easy to break, so use them for puzzles, games and teaching, not for secrets. To protect text properly, use encrypt text.
Frequently asked questions
Is the caesar cipher free?
Yes. The caesar cipher is completely free, with no account, sign-up or usage limit.
Is this secure enough for secret information?
No. Caesar, Vigenère and Atbash are centuries-old methods that you can break with pen and paper. They are fun for puzzles, treasure hunts and lessons. For real secrets, use Encrypt text (AES-256).
What is the difference between the methods?
Caesar shifts every letter a fixed number of places. Vigenère uses a keyword, so each letter shifts differently. Atbash reverses the alphabet: A becomes Z, B becomes Y.
Is my text stored?
No. Your text is processed in your browser and is not sent to a server or stored.