Caesar / ROT13 / Atbash Tool
Encrypt text with Caesar shift, ROT13, or Atbash substitution cipher.
Last reviewed by the Radiatus Cloud team
Output
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Three classic substitution ciphers in one place
Caesar, ROT13 and Atbash are the substitution ciphers everyone meets first: simple, historical, and perfect for puzzles and teaching. This tool encrypts and decrypts with all three, so you can shift text by any amount, apply the fixed ROT13 rotation, or mirror the alphabet with Atbash, without working out the substitutions by hand.
How each one works
A Caesar cipher shifts every letter by a fixed amount, so with a shift of three, A becomes D. ROT13 is simply a Caesar shift of thirteen, which has the neat property that applying it twice returns the original, so the same operation encodes and decodes. Atbash reverses the alphabet, mapping A to Z, B to Y and so on, which is also its own inverse. Seeing all three side by side makes the family resemblance clear.
For learning and puzzles, not for secrecy
These ciphers are a great way to learn how substitution works and to make and solve puzzles, but none of them provides real security: a Caesar cipher has only twenty-five possible shifts and can be broken by trying them all, and letter-frequency analysis cracks any simple substitution quickly. Treat them as educational and recreational. The encoding runs entirely in your browser.
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Frequently Asked Questions
What is the difference between the three ciphers?
Caesar shifts every letter by a chosen amount; ROT13 is a fixed Caesar shift of thirteen; Atbash reverses the alphabet so A maps to Z. All are simple letter substitutions.
Why does ROT13 use the same operation to encode and decode?
Because thirteen is half of twenty-six, applying a shift of thirteen twice returns the original letter, so one operation does both.
Are these ciphers secure?
No. They are for learning and puzzles. A Caesar cipher has only twenty-five shifts to try, and frequency analysis breaks any simple substitution quickly.
Can I choose the Caesar shift amount?
Yes. You can shift by any amount for Caesar, while ROT13 and Atbash use their fixed rules.
Is my text uploaded?
No. The encoding and decoding run entirely in your browser.
Privacy & Security
Processed locally in your browser. No data is sent to any server.
How to Use
Choose a cipher and paste text to encode/decode.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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