ROT13 and ROT47

A letter shift, not encryption

ROT13 moves each English letter 13 places. A becomes N, and N becomes A, so the same operation encodes and decodes. ROT47 does the same kind of shift over the printable ASCII range from ! to ~. Neither hides a secret from someone who knows the trick. Digits and Chinese are unchanged by ROT13.

How to use it

1. Paste the text. Choose ROT13 or ROT47.
2. Run it again on the result to get the original back. There is no separate decode mode.
3. The example Hello, world becomes Uryyb, jbeyq under ROT13. The comma and the space stay.

What moves

ROT13 changes only A–Z and a–z. Case is kept. Spaces, digits, punctuation and any character outside that range stay. ROT47 changes the 94 printable ASCII characters and leaves everything else, including Chinese and newlines. It is not Base64 and it is not a hash.

Where people use it

• Hiding a joke or a puzzle answer in a forum post.
• A reversible sample when you are explaining a Caesar shift.
• ROT47 when digits and punctuation should move too.

Questions