ROT13 Cipher – Encoder & Decoder
ROT13 (“rotate by 13 places”) is a special case of the classic Caesar Cipher. Instead of selecting your own shift, ROT13 always rotates each letter exactly 13 positions through the alphabet. Because the alphabet has 26 letters, applying ROT13 twice returns the text back to normal. It’s encryption… but with training wheels.
ROT13 has been used online for decades – hiding spoilers, masking punchlines, or giving puzzle fans a tiny bit of mystery before they inevitably decode it anyway. Not secure, but definitely fun.
How ROT13 Works
ROT13 is simply the Caesar Cipher with a fixed key:
ROT13 = Caesar shift of 13This means:
HELLO → URYYB
URYYB → HELLOAlphabet Mapping
| Letter | ROT13 | Letter | ROT13 |
|---|---|---|---|
| A | N | N | A |
| B | O | O | B |
| C | P | P | C |
| D | Q | Q | D |
| E | R | R | E |
| F | S | S | F |
| G | T | T | G |
| H | U | U | H |
| I | V | V | I |
| J | W | W | J |
| K | X | X | K |
| L | Y | Y | L |
| M | Z | Z | M |
Examples
Input:
The treasure is buried under the apple tree.ROT13 Output:
Gur gernfher vf ohevrq haqre gur nccyr gerr.ROT13 FAQ
What does ROT13 stand for?
It means “Rotate by 13”. Each letter is shifted 13 places through the alphabet.
Is ROT13 the same as the Caesar Cipher?
Yes. ROT13 is simply a Caesar Cipher with a fixed shift of 13.
Can ROT13 encrypt numbers?
No. ROT13 only works on letters A–Z. Numbers, punctuation, emojis and symbols don’t change.
Is ROT13 secure?
Not at all. It’s just for light obfuscation and puzzle fun.