Rotate letters by N positions (default 13). Free, private, runs in your browser.
100% private — your files and text never leave your browser. All processing happens locally on your device.
ROT-13 (shift = 13) is symmetric — applying it twice restores the original text.
ROT13 is a special case of the Caesar cipher that shifts every letter by 13 positions in the alphabet. Because the alphabet has 26 letters, applying ROT13 twice returns to the original text — a property called self-inverse. This makes it useful for hiding spoilers, puzzle answers, and mildly sensitive jokes in online forums and Usenet posts.
The tool generalizes to any shift from 1 to 25. Shift 1 becomes the classic Caesar cipher (as Julius Caesar reportedly used). Shift 3 is another historical favorite. Only shift 13 is self-inverse; for any other shift, you need to apply the negative shift (or 26 minus your original) to decrypt.
Since there are only 25 possible shifts, trying them all is trivial. The brute-force panel renders every shift at once so you can eyeball which row reads as natural language. This is the standard way to break any unknown Caesar-family cipher in puzzles, CTF challenges, and cryptanalysis exercises.
Yes. ROT13 runs entirely in your browser with zero network activity. Your text never leaves your device, and the tool doesn't log, store, or analyze any input.
The alphabet has 26 letters, and 13 + 13 = 26, so applying ROT13 twice brings you back to the original text. You don't need a separate decode step — just apply ROT13 again.
It shows all 25 possible shifts at once. If you don't know the key used to encode a message, scanning the table for the row that reads as readable text effectively breaks the cipher.
Only the basic Latin letters A-Z and a-z are shifted. Digits, punctuation, accented letters, and Unicode characters pass through unchanged.