ROT13 Encode & Decode
ROT13 ("rotate by 13 places") is a simple substitution cipher that replaces a letter with the 13th letter after it in the alphabet. It is a special case of the Caesar cipher which was developed in ancient Rome.
Mask spoilers or solve puzzles instantly in your browser with our secure ROT13 tool.
ROT13 Encode & Decode
What is ROT13?
ROT13 ("rotate by 13 places") is a simple substitution cipher that replaces a letter with the 13th letter after it in the alphabet. It is a special case of the Caesar cipher which was developed in ancient Rome.
How it works
Since the Latin alphabet has 26 letters, ROT13 is its own inverse. Applying ROT13 to a piece of text twice recovers the original text.
Common Usage
ROT13 is typicaly used in online forums as a means of hiding spoilers, punchlines, and offensive jokes from the casual glance.
Like all tools on CuscusLab, ROT13 processing happens entirely in your browser. Your data never leaves your device. 100% Private. 100% Secure.
Why use ROT13?
ROT13 is the industry standard for hiding spoilers in online discussions. It is not meant for security, but rather for "obfuscation"—if you require actual data encoding for transmission, use our Base64 tool instead.
A Secure Workspace
Even for simple text masking, your privacy matters. CuscusLab ensures that your input is never sent to a server. All transformations happen locally using JavaScript in your browser, keeping your data confidential.