ROT13 Encoder
ROT13 encode decode
ROT13 encode decode Runs locally in your browser
ROT13 is its own inverse, so running the tool again restores the original text.
About the
The ROT13 Encoder shifts every letter thirteen places through the alphabet, which is the classic way to hide a spoiler, a puzzle answer or a punchline in plain sight. The trick is that thirteen is half of twenty-six, so the same operation both encodes and decodes: running the tool twice returns the original text. Only letters move; digits, punctuation and spacing are left alone.
Where people use the
- Hiding a spoiler or a puzzle answer in plain text.
- Obfuscating a punchline that someone might read by accident.
- Teaching how a simple substitution cipher works.
- Making a string unreadable at a glance without any real security.
How to use the
- 1
Paste the text
Type or paste anything. Letters are shifted; everything else passes through unchanged.
- 2
Run it
Each letter moves thirteen places, wrapping around at the end of the alphabet.
- 3
Share the result
The output is unreadable at a glance but trivially reversible, which is exactly what a spoiler needs.
- 4
Run it again to reveal
Because ROT13 is its own inverse, pasting the result back in restores the original text.
Tips and best practices
- Run it twice to get your original text back.
- Never use it for anything that actually needs protecting.
- Use the Caesar Cipher tool if you want a shift other than thirteen.
Frequently asked questions
Is ROT13 encryption?
No. It provides no security at all. Anyone can reverse it, which is the point when you are hiding a spoiler rather than protecting a secret.
Why does it work both ways?
Because there are twenty-six letters and the shift is thirteen. Shifting by thirteen twice is a shift of twenty-six, which is a full turn back to the start.
What happens to numbers and punctuation?
Nothing. Only the letters a to z and A to Z are shifted, and case is preserved.
Is it the same as a Caesar cipher?
It is one specific case of it, with a shift of thirteen. The Caesar Cipher tool lets you use any shift.
Does it handle accented letters?
No. Only the unaccented English alphabet is shifted; accented characters are passed through unchanged.