Tools / Atbash Cipher
Atbash Cipher Decoder
Atbash maps each letter to its mirror in the alphabet: A becomes Z, B becomes Y, and so on through M and N. There is no key - the same operation encodes and decodes.
Output
Output appears here.A ↔ Z, B ↔ Y, C ↔ X, ... M ↔ N
When to suspect Atbash
Atbash predates Caesar by centuries (it appears in the Hebrew Bible) and shows up in CTF challenges as a low-effort trap. If a string looks like English ciphertext but does not decode under any ROT shift, try Atbash. Common giveaways: high frequency of v (which maps to E), g (T), and z (A).
For more general single-alphabet substitution where each letter maps to a fixed but arbitrary letter, use the Frequency Analysis tool. For shifted alphabets, use the ROT / Caesar Cipher tool. If you do not know what cipher you have, paste it into the Cipher Identifier first - it tries Atbash automatically.