ROT13 & Caesar Cipher
Rotate ASCII letters with ROT13 or a chosen Caesar shift while preserving case and other characters.
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How to use
ROT13 always rotates A–Z by 13 and is its own inverse. Caesar mode uses the selected shift; Decode applies the inverse shift. Only unaccented English ASCII letters participate.
Example
Input
Hello, مرحبا!
Output
Uryyb, مرحبا!
Limitations
Non-ASCII letters, digits, punctuation, Arabic, and emoji are unchanged. Caesar ciphers are historically interesting obfuscation and are not secure encryption.
Frequently Asked Questions
How do I reverse ROT13?
Apply ROT13 a second time. A shift of 13 is its own inverse.
Why are Arabic or accented letters unchanged?
The explicit cipher alphabet is ASCII A–Z and a–z. Extending shifts to other scripts would require a different, agreed alphabet.