Atbash Cipher
Mirror the alphabet: A↔Z, B↔Y, C↔X. The same operation both encodes and decodes.
100% client-side · no upload
What is the Atbash cipher?
The Atbash cipher is one of the simplest substitution ciphers. It maps each letter to its reverse counterpart in the alphabet: the first letter (A) maps to the last (Z), the second (B) to the second-to-last (Y), and so on. Numbers, spaces, and punctuation pass through unchanged. Because the mapping is its own inverse, the same operation both encrypts and decrypts.
How to use
- Paste or type your text in the input box.
- The Atbash-encoded output appears instantly below.
- To decode, paste the encoded text in the input — the original text appears in the output.
Related tools: ROT13, Caesar Cipher, Morse Code
よくある質問
- What is the Atbash cipher?
- The Atbash cipher is a substitution cipher that maps each letter to its mirror in the alphabet: A↔Z, B↔Y, C↔X, etc. It originated in the Hebrew alphabet and appears in the Bible (e.g. "Sheshach" for "Babel" in Jeremiah 25:26). Applying Atbash twice returns the original text.
- Does my data leave my device?
- No. The Atbash transformation runs entirely in your browser as pure JavaScript.
- Does it work on mobile?
- Yes. Text is transformed instantly as you type in any modern mobile browser.