Last updated October 13, 2026 · Report an error
The Atbash cipher is one of the oldest known substitution ciphers, originally used for the Hebrew alphabet — it simply mirrors each letter to its opposite position in the alphabet.
This tool applies the Atbash cipher to any text, mapping A to Z, B to Y, and so on.
How it works
Enter your text. Every letter is mirrored to its opposite position in the alphabet (A becomes Z, B becomes Y, and so on), while non-letter characters are left unchanged.
- Enter text.
- Click Calculate to see your results.
Examples
Mirroring "Hello"
"Hello" becomes "Svool" when run through the Atbash cipher.
Who should use it
- Word puzzles and simple text obfuscation for games.
- Teaching the concept of substitution ciphers.
Industry applications
- Cryptography education
- Games and puzzles
Advantages
- Extremely simple to apply and verify by hand.
- Self-reciprocal — the same operation both encodes and decodes.
Limitations
- No key at all, so it provides no real security whatsoever.
Common mistakes to avoid
- Expecting a separate "decode" mode — Atbash decoding is identical to encoding since the mapping is its own inverse.
- Assuming Atbash offers any real security, since there's no secret key involved at all.
Best practices
- Use Atbash for puzzles, wordplay, or teaching the concept of substitution ciphers — it has no practical security use.
Tips
- Because Atbash is self-reciprocal, you can verify your result is correct by running the output back through the tool and checking that you get the original text back.
Frequently asked questions
Yes, with no signup and no limit on how many conversions you run.
Just run it through this same tool again — because the mapping is symmetric (A↔Z, B↔Y, etc.), applying Atbash twice returns the original text.
No — with a fixed, well-known mapping and no key at all, it offers essentially no real security and is used for puzzles and history, not protecting data.
It was originally used to encode the Hebrew alphabet and is one of the earliest known substitution ciphers, later adapted to the Latin alphabet.