ROT13 Cipher
Rotate letters by 13 positions. Apply twice to decode. Non-letter characters are preserved.
100% client-side · no upload
What is ROT13?
ROT13 is a simple letter substitution cipher. Each letter is replaced by the letter 13 positions after it in the Latin alphabet (wrapping at Z back to A). For example A→N, B→O, … N→A, O→B. Numbers, punctuation, and spaces are not changed. Because the alphabet has 26 letters, applying ROT13 twice returns the original text.
How to use
- Paste your text into the input box — the ROT13 result appears instantly.
- To decode ROT13 text, paste it in as the input — the output will be the original.
- Click Copy to copy the result to your clipboard.
Related tools: Caesar Cipher, Atbash Cipher, Morse Code
よくある質問
- What is ROT13?
- ROT13 ("rotate by 13") shifts each letter in the alphabet 13 positions forward. Because the English alphabet has 26 letters, applying ROT13 twice returns the original text. It is commonly used to hide spoilers in forum posts and to obfuscate text without true encryption.
- Does my data leave my device?
- No. The ROT13 transformation is pure JavaScript running entirely in your browser.
- Does it work on mobile?
- Yes. The tool works on any modern mobile browser. Text is transformed instantly as you type.