Guides5 min read
Atbash Cipher: The Mirror-Alphabet Math
Atbash cipher: encode, decode, and see exactly how the mirror-alphabet math works, with a worked example and a free browser-based tool — no account needed.
Atbash cipher
Encode or decode text with the mirror-alphabet cipher. Free, private — nothing leaves your device.
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Atbash0 characters
Your Atbash-transformed text will appear here.Everything you need to mirror a message
Self-inverse by design
Run your result back through the tool and you get the original text — encoding and decoding are the same operation.
Live transformation
The mirrored text updates instantly as you type — no button to click, no mode to pick.
100% private
Runs entirely in your browser. Nothing you type is uploaded or stored.
Copy or download
Grab the result with one click, or download it as a .txt file.
Encode or decode in three steps
- 1
Type or paste your text
Enter the text you want to transform — Atbash works the same way whether you're encoding or decoding.
- 2
Read the mirrored result
Every letter is instantly swapped for its mirror in the alphabet — A becomes Z, B becomes Y, and so on.
- 3
Copy or download it
The Atbash text updates live as you type — copy it or download it as a .txt file.
Built for learning, puzzles, and quick checks
Atbash is one of the oldest known substitution ciphers — useful for teaching, puzzles, and historical curiosity, not for real security.
Learning classical cryptography
See one of the oldest known substitution ciphers work in real time — a common example in intro crypto and history-of-cryptography courses.
Puzzles and escape rooms
Atbash is a favorite in puzzle hunts and escape-room clues — mirror the text back in seconds.
Checking a homework answer
Verify a hand-worked Atbash answer instantly instead of counting mirror positions by hand.
Historical and biblical curiosity
Try the cipher tradition tied to the Hebrew alphabet and referenced in the Book of Jeremiah.
Frequently asked questions
What is the Atbash cipher?
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Atbash is a substitution cipher that maps each letter to its mirror position in the alphabet: A becomes Z, B becomes Y, C becomes X, and so on through the middle. There's no key or shift amount to choose — the mapping is always the same.
Where did the Atbash cipher come from?
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Atbash originated as a cipher for the Hebrew alphabet and is thousands of years old — it appears in the Bible, including a well-known instance in the Book of Jeremiah. It was later adapted to the Latin alphabet used by English and other languages.
Is the Atbash cipher secure?
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No — it has no key at all, so once someone recognizes the pattern it's instantly reversible. It's a classical and educational cipher, useful for puzzles and history, not for protecting anything sensitive.
Why does running Atbash twice return the original text?
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Atbash is self-inverse: mirroring a letter's position and then mirroring it again lands back on the original letter. Encode a message with Atbash and running it through Atbash a second time decodes it — the same operation does both jobs.
How is Atbash different from a Caesar cipher?
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A Caesar cipher shifts letters by a chosen amount, so you need to know (or guess) the shift to reverse it. Atbash has a single fixed mapping with nothing to guess — if you know it's Atbash, you already know how to reverse it.
How do you decode Atbash by hand?
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Pair each letter with its mirror: A↔Z, B↔Y, C↔X, and so on to the middle (M↔N). To decode a message, replace every letter with its mirror partner — the same swap used to encode it. No key or offset to track, just the fixed A-Z mirror. This tool does the swap instantly, but the by-hand math is the same either way.
Is my text uploaded anywhere?
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No. Everything runs in your browser — nothing you type is sent to a server.
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Try the Atbash cipher now
Free, no account needed.