Text & Writing
ROT13 / Caesar Cipher
ROT13 / Caesar Cipher shifts every letter in your text by a chosen amount, encoding it into a simple substitution cipher or decoding it back again. ROT13 is the classic shift-by-13 used across forums to hide spoilers, and you can pick any other shift amount for a custom Caesar cipher.
It's handy for puzzle creators, students learning basic cryptography, or anyone masking a spoiler in a forum post. The shifting happens instantly in your browser using JavaScript, so your original text is never sent to a server.
How to Use the ROT13 / Caesar Cipher
- Open the ROT13 / Caesar Cipher tool.
- Paste in the text you want to encode or decode.
- Set the shift amount, or leave it at 13 for classic ROT13.
- Copy the shifted result.
Frequently Asked Questions
What shift does ROT13 use?
ROT13 shifts every letter by exactly 13 positions in the alphabet, and applying it twice returns the original text.
Can I use a shift amount other than 13?
Yes, you can set any shift value to create a custom Caesar cipher instead of the standard ROT13.
Does the cipher affect numbers or punctuation?
No, only alphabetic letters are shifted; numbers, spaces, and punctuation are left unchanged.