How to encode or decode ROT13
- Paste your text into Input. It can be plain text, ROT13 or a mix of both.
- The result appears straight away. Plain text comes out scrambled and ROT13 comes out readable, because one step does both.
- Copy the result. Paste it back in to turn it the other way again.
Where ROT13 is used
ROT13 became a habit on Usenet newsgroups, where people used it for punchlines, spoilers and offensive jokes so readers had to choose to decode them. It’s still used the same way on forums and in puzzle hunts, and the hints on geocache listings are written in it. Programmers meet it as a classic beginner exercise and as a joke example of “encryption” that protects nothing.
The ROT13 table
Each letter in the top row swaps with the letter below it, and the other way round:
A B C D E F G H I J K L M
N O P Q R S T U V W X Y ZSo “hello” becomes “uryyb”, and “uryyb” becomes “hello” again. On Linux or macOS, the command tr 'A-Za-z' 'N-ZA-Mn-za-m' does the same thing in a terminal.