Atbash Cipher
Encode and decode text using the Atbash cipher. Reverses the alphabet (A↔Z, B↔Y, C↔X…); non-letters pass through unchanged. Self-inverse — running it twice returns the original text.
Input
Output
Atbash is symmetric — apply it again to decode.
Guides
What is the Atbash cipher?
The Atbash cipher is one of the oldest known substitution ciphers, originally devised for the Hebrew alphabet and later applied to Latin script. It works by reversing the alphabet: the first letter swaps with the last, the second with the second-to-last, and so on — A becomes Z, B becomes Y, C becomes X, all the way through to Z becoming A. The name comes from the first, last, second, and second-to-last letters of the Hebrew alphabet (Aleph, Taw, Bet, Shin — "AT-BASH"). It even appears in the Hebrew Bible, where scholars believe it was used to conceal certain names.
How this tool works
- Type or paste your text into the Input Text box.
- The Atbash Output updates automatically as you type — there's no shift amount or mode to configure, since Atbash always maps each letter to its mirror position in the alphabet.
Letter case is preserved (uppercase stays uppercase, lowercase stays lowercase), and anything that isn't a letter — numbers, punctuation, spaces, emoji — passes through unchanged.
Encoding and decoding are the same operation
Unlike the Caesar cipher, Atbash needs no key and no mode switch. Because it's a fixed, self-inverse mapping, running the same text through Atbash twice always returns the original text. To decode an Atbash-encoded message, just paste it back into this tool — you'll get the original text out.
Is the Atbash cipher secure?
No. With a fixed, publicly known mapping and no key at all, Atbash offers no real security — anyone who recognizes the pattern can decode it instantly, and it falls to basic letter-frequency analysis just as easily as any other simple substitution cipher. It's best suited for puzzles, teaching cryptography basics, geocaching clues, and historical curiosity — never for protecting sensitive information. For real encryption, use a modern algorithm such as AES.
Common uses
- Solving or creating puzzle-hunt and geocaching clues
- Teaching the basics of substitution ciphers in a classroom setting
- Recreational cryptography and escape-room style games
- Recognizing Atbash-encoded text in historical or literary contexts
Privacy
This tool runs entirely in your browser. Your text is never uploaded to a server.