Online Tool Store
ROT13 Encoder
Encode or decode text with the classic ROT13 letter-shift cipher, updated live as you type. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
ROT13 result
ROT13 is its own inverse — running it twice returns the original text.
How it works
- Type or paste text into the input box.
- Each letter is shifted 13 places through the alphabet, wrapping from Z back to A.
- Copy the result, or paste it back in to decode it — ROT13 works the same both ways.
The formula
For each letter, new position = (original position − alphabet start + 13) mod 26, then map back to a letter. Case is preserved, and non-letters are left untouched.
FAQ
Is ROT13 secure encryption?
No — it's a trivial letter-shift cipher used mainly to obscure spoilers or punchlines from casual view, not to protect sensitive data.
Why is running it twice the same as doing nothing?
ROT13 shifts each letter 13 places, and the alphabet has 26 letters, so shifting twice (26 places) lands back on the original letter.
Do numbers and punctuation change?
No — only letters A-Z and a-z are shifted; numbers, spaces, and punctuation pass through unchanged.
Is my text sent anywhere?
No — the shift is a simple character-code calculation that runs entirely in your browser.
How we compare
| Feature | Online Tool Store | rot13.com | Command-line tr |
|---|---|---|---|
| No terminal required | ✓ | ✓ | ✗ |
| Live as-you-type conversion | ✓ | ✓ | ✗ |
| No sign-up | ✓ | ✓ | ✓ |
If you just need a quick spoiler-hider without leaving this site, ROT13 Encoder gets you there in one paste.