Atbash Cipher Tool
Encode and decode text with the Atbash cipher, which mirrors the alphabet so A becomes Z and B becomes Y. Works in Latin, Hebrew, Greek and Cyrillic, with a live mapping table and step-by-step view.
100% client-side · A classical cipher for learning, not for real secrets
Mapping table
Each letter and its mirror. Pairs used by your text are highlighted.
Step by step
The Atbash cipher has no key and can be decoded by anyone who recognizes it. Use it to learn or for puzzles, never to protect real information.
How the Atbash Cipher Works
Write the alphabet forwards, then write it backwards underneath. Every letter is replaced by the one below it: A B C ... X Y Z becomes Z Y X ... C B A, so HELLO becomes SVOOL. In an alphabet of n letters, position p maps to position n + 1 - p.
Because the mapping is a perfect mirror, doing it twice restores the original, so one operation both encodes and decodes. There is no key to choose and nothing to keep secret, which is why Atbash is a curiosity rather than a defence. See how its relatives work in our Caesar cipher, Affine cipher and Vigenère cipher tools.
Live Results
The result updates as you type, with no encode or decode buttons to choose between
Four Alphabets
Latin, Hebrew (the original), Greek and Russian Cyrillic
Mapping Table
See every pair, with the ones your text uses highlighted
Step by Step
Positions and mirrored positions for the first letters of your text
Honest Limits
Clear that Atbash has no key and offers no real protection
Private by Design
Runs in your browser. Nothing is uploaded, saved or logged
Explore more free tools in our security tools collection, including our strong random password generator.
Frequently Asked Questions
1. What is the Atbash cipher?
Atbash is one of the oldest known ciphers. It was first used with the Hebrew alphabet, and its name comes from the way it pairs letters: aleph (first) with tav (last), then beth (second) with shin (second-last), giving A-T-B-Sh. Each letter is replaced by its mirror image in the alphabet, so in Latin A becomes Z, B becomes Y and HELLO becomes SVOOL.
2. How does the mirroring work?
In an alphabet of n letters, the letter in position p becomes the letter in position n + 1 - p. In the 26-letter Latin alphabet that is 27 - p, so H (8th) becomes S (19th). The Step-by-step view below the result shows this for the first letters of your text, and the mapping table highlights every pair your text uses.
3. Why are encoding and decoding the same operation?
Atbash is reciprocal: mirroring a mirrored letter brings you back to the original. If A becomes Z, then Z becomes A. So there is no separate decode step; paste an Atbash message into the tool and the result is the plain text. The Use result as message button lets you check this by round-tripping your text.
4. Is the Atbash cipher secure?
No. It has no key at all, so anyone who knows it is Atbash can decode a message instantly, and without that knowledge it falls to frequency analysis like any simple substitution cipher. It is a special case of the Affine cipher (with a = 25 and b = 25) and a relative of the Caesar cipher. Use it for puzzles and learning, never to protect real information; for that use a modern cipher such as AES.
5. Which alphabets does the tool support, and how are special letters handled?
Latin (A-Z, 26 letters), Hebrew (22 letters), Greek (24 letters) and Russian Cyrillic (33 letters, including ё). Case is kept where the alphabet has it. The Hebrew final forms (ך ם ן ף ץ) are treated like their regular forms and the result is written with regular forms, and Greek final sigma (ς) is treated like σ, so those few letters do not round-trip exactly. Accented letters and letters from other alphabets pass through unchanged.
6. What happens to numbers, spaces and punctuation?
By default they pass through unchanged. The classic cipher only mirrors letters. If you like, the Digits option also mirrors the digits (0 becomes 9, 1 becomes 8 and so on), which some puzzles use; it is applied in every alphabet.
7. Where has Atbash been used?
The best-known examples are in the Hebrew Bible, where the prophet Jeremiah uses the name Sheshach for Babylon (Babel): mirroring the Hebrew letters of Babel gives Sheshach. Today it appears mostly in puzzles, escape rooms, geocaching and books as a first example of a substitution cipher.
8. Is my text sent or stored anywhere?
No. Everything runs in your browser, the page's content security policy blocks outgoing network requests, and nothing you type is saved. The only thing the site remembers is your language choice for the menu.