ROT13 Encoder & Decoder - Free Online Tool

ROT13 ("rotate by 13 places") is a simple letter substitution cipher that replaces a letter with the letter 13 places after it in the alphabet. Applying ROT13 to a piece of text a second time restores the original text; this is its own inverse. It's a classic example of a Caesar cipher. Made famous on early internet forums like Usenet in the 1980s, ROT13 was used to hide spoilers, punchlines, or potentially offensive material from a casual glance. It offers no real cryptographic security and should not be used for anything sensitive. Our tool provides a quick and fun way to both encode and decode ROT13 messages, offering a glimpse into early internet culture and basic cryptography.