BYTETOOLS

Atbash Cipher Encoder & Decoder

Encode and decode text with the Atbash cipher, an ancient mirror-alphabet substitution where A maps to Z. Self-inverse, preserves case and punctuation.

Result

Svool, Dliow!

  • Classic mirror-alphabet substitution (A↔Z, B↔Y…)
  • Self-inverse — one action encodes and decodes
  • Preserves upper and lower case
  • Leaves digits, spaces and punctuation untouched
  • Instant live output as you type
  • Runs entirely in your browser

How to use the Atbash Cipher Encoder & Decoder

  1. 1

    Type or paste your message into the text box.

  2. 2

    Read the Atbash-transformed text appear instantly below.

  3. 3

    Run the same text through again to reverse it — Atbash is self-inverse.

  4. 4

    Copy the result to your clipboard.

About the Atbash Cipher Encoder & Decoder

The ByteTools Atbash Cipher transforms text with one of the oldest substitution ciphers, mapping each letter to its mirror image in the alphabet: A becomes Z, B becomes Y, and so on. Originally used with the Hebrew alphabet, it works the same way on the 26 Latin letters.

Because the mapping is a perfect mirror, Atbash is self-inverse — running it twice restores the original text, so a single button both encodes and decodes. It is a favourite for puzzles, geocaching clues, CTF challenges and classroom cryptography.

All processing is done locally in your browser with JavaScript. Nothing you type is uploaded or stored, and you can copy the mirrored result to your clipboard in one click.

Frequently asked questions

What is the Atbash cipher?

Atbash is a substitution cipher that reverses the alphabet, so the first letter maps to the last, the second to the second-last, and so on. A becomes Z, B becomes Y, M becomes N. It dates back to ancient Hebrew scribes.

Is Atbash the same when encoding and decoding?

Yes. Because the mapping is a fixed mirror, applying Atbash a second time undoes the first, returning the original text. That means there is no separate decode step — the same operation works both ways.

Does Atbash keep capital letters and punctuation?

This tool preserves the case of each letter, so a capital stays capital after mirroring. Digits, spaces and punctuation are passed through unchanged, keeping the overall shape of your message intact.

How is Atbash different from the Caesar cipher?

A Caesar cipher shifts every letter by the same fixed amount, while Atbash reverses the alphabet so each letter moves a different distance. Atbash has no adjustable key at all — the mapping is always the same mirror.

Is the Atbash cipher secure?

No. Atbash has a single fixed key and is trivial to reverse, so it offers no protection against anyone who recognises it. Use it for puzzles, teaching and light obfuscation, never for genuinely sensitive information.

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