About the Text to ROT13
ROT13 replaces each letter with the one thirteen positions further on, wrapping from Z back to A. Because the alphabet has twenty six letters, thirteen is exactly half, which gives the scheme its defining property: applying it twice returns the original text. One button therefore covers both directions, and no key is involved.
It began as a Usenet convention for hiding punchlines and film endings, and it still fills that role. Puzzle sites, escape room clues, crossword solutions and forum spoiler tags all use it because the reader has to make a deliberate choice to reveal the answer, while nobody is inconvenienced for more than a second.
Only the twenty six ASCII letters move. Digits, punctuation, spaces, line breaks and accented characters pass through unchanged, and letter case is preserved, so a capitalised sentence stays capitalised after the shift. The optional ROT13.5 variant also rotates digits by five places, which is handy when the thing you are hiding is a number such as a room code or a page reference.
This is obfuscation with no security value at all, since anyone can reverse it in a moment. For a shift you can choose yourself try Caesar Cipher, for punctuation as well as letters try ROT47, and to reveal text use ROT13 to Text.
How to use
- Type or paste the text you want to hide.
- Tick Also rotate digits if the secret contains numbers.
- Copy the rotated text, and tell readers it is ROT13 so they know how to read it.
Common questions
- How do I read a ROT13 message?
- Run it through the same shift again. Thirteen plus thirteen is twenty six, a full circle, so encoding twice restores the original.
- Are accented letters rotated?
- No. Only the twenty six unaccented ASCII letters move, so é and ñ appear unchanged in the output.
- Is ROT13 secure?
- Not at all. It is a convention for hiding text from casual view, not a cipher, and it takes seconds to undo.
- What is ROT13.5?
- A variant that also rotates each digit by five, so 0 becomes 5 and 7 becomes 2. It is useful when numbers are part of the secret.