ROT13 Encoder/Decoder
Rotation Type
Select the cipher rotation amount
ROT13 (shift by 13, symmetric)
Input Text
Output Text
Quick Reference
Original:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
ROT13:
NOPQRSTUVWXYZABCDEFGHIJKLM
Related Tools
What is ROT13?
ROT13 ("rotate by 13 places") is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet. Because there are 26 letters in the English alphabet, applying ROT13 twice returns the original text - making it symmetric and self-inverse.
This free online tool lets you encode and decode text using ROT13 and other rotation ciphers including ROT1 (Caesar cipher), ROT5, and ROT47. The transformation happens instantly as you type.
All processing happens directly in your browser - your data never leaves your device.
ROT Cipher Variations
ROT13 (Standard)
The most common rotation cipher. Shifts letters by 13 positions. Since 13 is half of 26, encoding and decoding are the same operation.
ROT1 (Caesar Cipher)
The classic Caesar cipher shifts each letter by 1 position. Named after Julius Caesar who reportedly used it for military communications.
ROT5
Shifts letters by 5 positions. Sometimes combined with ROT13 to create ROT18 for letters and ROT5 for numbers separately.
ROT47
Extended cipher that rotates all printable ASCII characters (33-126), including numbers, letters, and symbols. More thorough obfuscation.
Frequently Asked Questions
Is ROT13 secure for encryption?
No, ROT13 provides no security whatsoever. It's trivially reversible and anyone who knows about ROT13 can decode it instantly. It's only suitable for casual obfuscation like hiding spoilers or puzzle answers - never for protecting sensitive information.
Why is ROT13 symmetric?
ROT13 is symmetric because 13 is exactly half of 26 (the number of letters in the English alphabet). Shifting by 13 twice brings you back to the original letter: A → N → A. This means the same function is used for both encoding and decoding.
What happens to numbers and symbols?
In standard ROT13, only letters are rotated - numbers, spaces, and symbols remain unchanged. If you need to obfuscate everything, use ROT47 which rotates all printable ASCII characters including numbers and symbols.
Is my data sent to a server?
No. All encoding and decoding happens entirely in your browser using JavaScript. Your data never leaves your device, making this tool completely private.