ROT13 encoder and decoder
One button encodes and decodes — ROT13 is its own reverse.
Paste text and press the button to shift every letter thirteen places through the alphabet. Because the alphabet has twenty-six letters, shifting by thirteen a second time brings you straight back — so the same button both scrambles and unscrambles. Letters keep their case, and digits, spaces and punctuation are left exactly as they are.
Runs entirely in your browser. Your text is never uploaded — open DevTools, Network tab, and you will see zero requests while you use this tool.
How to use it
- Paste your text into the box.
- Press "ROT13 encode / decode".
- Press it again on the result to get your original text back.
- Copy the output, or download it as a .txt file.
What this tool does
ROT13, short for "rotate by 13 places", replaces each letter with the one thirteen positions further along the alphabet, wrapping around from Z back to A. A becomes N, B becomes O, and so on. The letter thirteen steps past N is A again, which is why the transformation is a perfect mirror of itself: apply it twice and you are back where you started.
Only the twenty-six basic Latin letters move. Numbers, accented letters, emoji, spaces and punctuation pass through untouched, so the shape of your text — line breaks, spacing, symbols — is preserved.
Examples
"Hello, World!" becomes "Uryyb, Jbeyq!". Run ROT13 on that and you get "Hello, World!" back. "The quick brown fox" becomes "Gur dhvpx oebja sbk". A phone number like "call 555-2020" keeps its digits: "pnyy 555-2020".
When you need it
The classic use is hiding a spoiler, a puzzle answer or a joke punchline in plain sight. Anyone who wants to read it can, but the text will not be understood by accident or picked up at a glance. Usenet and old forums used it for exactly this, and puzzle communities still do.
It also appears in programming as a harmless example cipher, in capture-the-flag puzzles, and any time you want to make a short string non-obvious without any real protection. If you are learning about ciphers, it is the simplest possible Caesar shift and a good place to start.
ROT13 is not encryption
This is worth stating plainly: ROT13 provides no security whatsoever. There is no key, the method is public, and anyone can reverse it in seconds — including this page. Never use it to protect a password, a private message or anything that actually needs to stay secret. It obscures text from casual reading, nothing more. For real protection you need genuine encryption, which is a completely different thing.
Doing it without this tool
Command line: echo "text" | tr 'A-Za-z' 'N-ZA-Mn-za-m' does exactly this on Linux and macOS. It is a neat one-liner and shows how simple the transform is.
Python: codecs.encode("text", "rot13") is built in.
By hand: write the alphabet out, write it again shifted by thirteen underneath, and swap. Slow, but it is genuinely all there is to it — no maths beyond counting to thirteen.
Privacy: your text never leaves your browser
Everything on this page runs in your browser with JavaScript. The text you paste is never sent to a server, no account is required and nothing is stored anywhere. You can confirm it: open your browser developer tools, switch to the Network tab and use the tool — you will see zero requests go out. For anything sensitive, that is the whole point.
Related tools
Frequently asked questions
Because shifting by thirteen twice returns each letter to where it started. ROT13 is its own inverse, so encoding and decoding are the same operation.
No. Only the twenty-six basic Latin letters are rotated. Digits, punctuation, spaces, emoji and accented characters are left exactly as they were.
Not at all. It has no key and can be reversed instantly by anyone. Use it to hide spoilers or puzzle answers, never to protect anything that must stay secret.
Case is preserved. An uppercase letter maps to an uppercase letter and a lowercase letter to a lowercase one.
ROT47 is a related cipher that also shifts digits and punctuation across a wider character range. This tool does classic ROT13, which moves letters only.
No. The rotation happens in your browser and the text never leaves your device.