ROT13 decoder

What ROT13 is for

ROT13 shifts every letter 13 places: A becomes N, N becomes A. The alphabet has 26 letters, so doing it twice gets you back where you started, and one button both hides and reveals a message. Nobody uses it for secrecy. It's for things you shouldn't read by accident: spoilers, puzzle answers, punchlines. It's been doing that job on the internet since the Usenet days.

The other ROTs

• ROT5 applies the same trick to digits, turning each one five places round 0–9. 2026 becomes 7571.
• ROT18 is ROT13 and ROT5 together, so letters and digits both change.
• ROT47 rotates every printable ASCII character from ! to ~, so punctuation is scrambled as well. The result looks like line noise: Hello becomes w6==@.

All four undo themselves. If ROT13 doesn't crack your message, try a different shift with the Caesar cipher tool; it ranks all 25 for you.

Recognising ROT13

Common English words have familiar ROT13 forms, and once you've seen them you'll spot them everywhere: gur is the, naq is and, bs is of, vf is is. A text full of gur is almost certainly ROT13.