Encrypt or decrypt with no key. 100% local processing in your browser. No input text is sent to the server.
Atbash has no secret key: each letter is replaced by its opposite in the alphabet. Spaces, punctuation and accents are preserved.
Atbash cipher encoder and decoder
Atbash is a monoalphabetic substitution in which the alphabet is reversed: A becomes Z, B becomes Y, and Z becomes A. Applying the transformation twice restores the original message.
For example, HELLO WORLD becomes SVOOL DLIOW. Atbash is useful for puzzles and learning about classical ciphers, not for protecting sensitive information.