ROT13 Encoder / Decoder
Encode and decode text with ROT13 cipher. Also supports Caesar cipher with any shift (1–25). Free and instant.
How to use the ROT13
ROT13 — the simplest cipher
ROT13 replaces each letter with the letter 13 positions ahead in the alphabet (A→N, B→O…). Because the alphabet has 26 letters, applying ROT13 twice returns the original text — making it self-reversing. It's used to hide spoilers and answers in online forums.
Caesar cipher
Julius Caesar used a shift-3 cipher to protect military messages. The Caesar cipher shifts every letter by a fixed number. With a shift of 3: A→D, B→E, C→F. To decode, shift back by the same amount (or use shift 23 to decode shift 3). ROT13 is simply a Caesar cipher with shift 13.
Frequently asked questions
Is the ROT13 free to use?
Yes, the ROT13 is completely free. There is no sign-up, no account required, and no limit on how often you can use it.
Is my text private when using the ROT13?
Yes, all text processing happens in your browser. Your text is not sent to any server and is not stored anywhere outside your device.
What devices does the ROT13 work on?
The ROT13 works on any device with a modern web browser — desktop, laptop, tablet, or phone. It is mobile-friendly and works offline once the page has loaded.