Atbash Cipher
Atbash cipher reverses the English alphabet, A↔Z and a↔z, with no key; applying it again restores the original text.
Ready. Fixed alphabet reversal; no shift or key is required.
Original alphabet-reversal checks
We created four text samples, applied this page’s fixed reversal and applied it again to the result. Every recovered input matched the original, including case and nonletters. A separate Python calculation matched each output. The table was generated from those calculations, not copied from another cipher tool.
| Original text | Atbash output | Applied again |
|---|---|---|
| ABCDEFGHIJKLMNOPQRSTUVWXYZ | ZYXWVUTSRQPONMLKJIHGFEDCBA | ABCDEFGHIJKLMNOPQRSTUVWXYZ |
| Hello, World! 123 | Svool, Dliow! 123 | Hello, World! 123 |
| Abc XYZ 09 é 🚀 | Zyx CBA 09 é 🚀 | Abc XYZ 09 é 🚀 |
| Line 1\nLine 2 | Ormv 1\nOrmv 2 | Line 1\nLine 2 |
The alphabet row reversed all English uppercase letters. Hello, World! 123 produced Svool, Dliow! 123 and returned to the original on the second application. The mixed sample preserved digits, punctuation, the accented character and emoji. The final sample preserved its real line break; the table displays it as \n for visibility.
To reproduce a row, paste its original text and apply Atbash, then use Apply again to result. Compare the final result with the original. There is no key or direction setting because both directions use the same fixed mapping.
Alphabet and nonletters
This version supports English A–Z and a–z only. Uppercase letters remain uppercase and lowercase letters remain lowercase. The mapping reverses each alphabet in place; it does not reverse the order of characters in the sentence. Digits, punctuation, spaces, line breaks, accented letters, emoji and other characters stay unchanged. There is no custom alphabet.
Is Atbash the same as Caesar or ROT13?
No. Atbash reverses the alphabet. Caesar shifts each letter by a fixed distance, and ROT13 is the Caesar shift of 13. Use the Caesar cipher decoder and ROT13 tool for that operation.
Is Atbash the same as Vigenere?
No. Vigenere applies repeated shifts from a key supplied by the user. Atbash has one fixed reversed mapping and no key. Use the Vigenere encrypt and decrypt tool for keyed shifts.
Does Atbash keep text secret?
No. The mapping is public and directly reversible. Use it for exercises and puzzles, not protection of confidential information.
Input, output and limits
Paste one text sequence and copy the resulting text. Input is limited to 20,000 characters per run. Processing runs locally without login, file upload, batch mode or saved history. The tool does not upload your text or require a daily conversion allowance.
Related representation walkthrough
This existing video demonstrates hexadecimal byte input and Base64 output. It is a related representation walkthrough, not an Atbash tutorial.
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To display separate classical transformations without identifying or cracking a cipher, use the Classic cipher result comparison tool.