ROT13 Caesar Cipher
ROT13 Caesar Cipher shifts basic Latin letters by a selected amount, with 13 as the default.
Example: rot13 caesar cipher
abc
nop
How to use this tool
- Enter text containing Latin letters.
- Choose encode or decode and a shift from 1 to 25.
- Check the transformed letters and unchanged punctuation.
How the shift works
The tool rotates ASCII A–Z and a–z through the 26-letter alphabet while preserving case. With shift 13, “abc” becomes “nop”; the same shift decodes the result. Other shifts decode by moving in the opposite direction. Spaces, digits, punctuation, and non-Latin letters remain unchanged.
When this is useful
Use it for a simple puzzle, spoiler masking, or demonstrating substitution ciphers. It is not a way to protect private content; trying all 25 shifts is trivial. Case Converter changes capitalization rather than alphabet positions, and Unicode style tools replace glyphs rather than performing an alphabet rotation.
Check language and direction
The control accepts shifts 1 through 25. For any other shift, encode and decode are different operations; verify the selected direction before copying output. Accented Latin letters and other scripts are not part of this tool’s 26-letter alphabet.
Questions people ask
Does ROT13 encrypt securely?
No; it is a simple reversible letter substitution.
Are numbers shifted?
No; numbers and punctuation stay unchanged.
Will it shift accented letters?
No; only basic ASCII Latin letters are rotated.