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Atbash cipher

Apply the Atbash cipher to any text. Each letter maps to its alphabet-reverse counterpart: a becomes z, b becomes y, ... z becomes a. Atbash is its own inverse: applying it twice returns the original. Digits, punctuation, accented characters, and non-Latin scripts pass through unchanged. This is a classical cipher with origins in Hebrew scripture and is not encryption. The transform runs in your browser; nothing uploads.

Input
Line 1:1 LF cloud_done Saved locally
Result Atbash Cipher
0 lines 0 chars

Atbash, the alphabet-reversal cipher

Atbash is a substitution cipher that maps each letter to its mirror across the alphabet: a swaps with z, b with y, c with x, and so on through m swapping with n. The name comes from the first and last letters of the Hebrew alphabet (Aleph-Tav, Bet-Shin), where the cipher originated as a way to obscure scripture.

Like ROT13, Atbash is involutive: applying it twice returns the original. There is no separate decode function. Encoding HELLO gives SVOOL; encoding SVOOL gives HELLO. The implementation here is base + 25 - (code - base), which works the same for uppercase and lowercase letters, preserving case.

Only ASCII letters a-z and A-Z are transformed. Digits, punctuation, whitespace, accented Latin characters, and non-Latin scripts pass through unchanged. Atbash is a classical / historical cipher and is not encryption: anyone who knows what Atbash is can decode it instantly by re-applying the same transform. Use it for puzzles, ARG content, and as a teaching example. For other classical ciphers, see Caesar cipher and ROT13.

How to use atbash cipher

  1. 1Paste or type your text into the input panel on the left.
  2. 2The Atbash result appears in the output panel on the right as you type.
  3. 3Apply Atbash again to decode (the cipher is its own inverse).
  4. 4Click Copy in the output header to copy the result.
  5. 5For other classical ciphers, try Caesar cipher or ROT13.

Keyboard shortcuts

Drive TextResult without touching the mouse.

Shortcut Action
Ctrl FOpen the find & replace panel inside the input Plus
Ctrl ZUndo the last input change
Ctrl Shift ZRedo
Ctrl Shift EnterToggle fullscreen focus on the editor Plus
EscClose find & replace, or exit fullscreen
Ctrl KOpen the command palette to jump to any tool Plus
Ctrl SSave current workflow draft Plus
Ctrl PRun a saved workflow Plus

What this tool actually does

Alphabet-mirror substitution

Each letter maps to its 26-letter-alphabet mirror: a -> z, b -> y, m -> n, z -> a. Implementation: base + 25 - (code - base).

Self-inverse: encode and decode are the same

Applying Atbash to its own output returns the original. There is no separate decode button. This is the cipher's defining property and the reason it has a single named function.

Case preserved

Uppercase letters stay uppercase, lowercase stay lowercase. Hello becomes Svool: the capital H maps to capital S, the lowercase letters map to lowercase letters.

Non-letter characters pass through

Digits, punctuation, whitespace, accented Latin characters (é, ñ), and non-Latin scripts (Cyrillic, Greek, CJK, emoji) are untouched. Only the ASCII a-z A-Z range maps.

Not encryption

Atbash has zero key: there is nothing to guess. Anyone who knows the cipher decodes it in one step. Use it for puzzles and historical curiosity, not for anything that needs to stay secret.

Worked example

H -> S, e -> v, ... d -> w; the comma and space pass through. Apply Atbash to the output and you get the input back. For the Caesar shift family, see Caesar cipher.

Input
Hello, world!
Output
Svool, dliow!

Settings reference

Behaviour Effect on output
ASCII a-z letters Mirrored across the alphabet. a -> z, m -> n, z -> a.
ASCII A-Z letters Mirrored, case preserved. A -> Z, M -> N.
Digits 0-9 Pass through unchanged.
Punctuation and whitespace Pass through unchanged.
Accented Latin characters é, ñ, ü pass through unchanged. Atbash is ASCII-only.
Non-Latin scripts Cyrillic, Greek, CJK, emoji all pass through unchanged.
Self-inverse Apply Atbash twice to get the original input back. No separate decode setting.

FAQ

How do I decode Atbash?
Apply Atbash again. The cipher is its own inverse. Paste the encoded text into the input and the decoded text appears in the output. There is no decode-specific setting.
How is Atbash different from ROT13?
Both are involutive and ASCII-letter-only, but they use different mappings. ROT13 shifts every letter by 13 (a -> n, n -> a). Atbash mirrors across the alphabet (a -> z, z -> a). Different ciphertext, same self-inverse property.
Where does the name "Atbash" come from?
From Hebrew. A + T + B + SH: Aleph (1st letter) maps to Tav (last), Bet (2nd) maps to Shin (2nd-last), spelling out the cipher's pattern. Atbash appears in the Hebrew Bible (Jeremiah, the word "Sheshach") as a coded reference.
Does Atbash affect digits or accented letters?
No. Only ASCII a-z and A-Z are mapped. Digits, punctuation, whitespace, accented characters (é, ñ), and non-Latin scripts all pass through unchanged.
Is Atbash secure?
No. There is no key, so anyone who knows the cipher exists can decode any Atbash text in one step. Use it for puzzles, ARGs, and as a teaching example, not for anything that needs to stay secret.

Also known as

atbash cipher atbash encoder decoder atbash online reverse alphabet cipher mirror alphabet cipher classical cipher converter hebrew cipher atbash translator