ROT13 Encoder & Decoder
Rotate letters 13 places to hide or reveal ROT13 text — instant, private, and free in your browser.
ROT13 is its own inverse: running the same text through a second time gives you the original back, so one button both encodes and decodes.
How to Use the ROT13 Encoder & Decoder
- Type or paste your text into the input box. Plain text becomes ROT13, and ROT13 text becomes readable again — the same operation does both.
- Tick "Also rotate digits (ROT5)" if you want 0–9 shifted by five places as well. That combination is often called ROT18 or ROT13.5.
- Click "Apply ROT13" to run the conversion. The result panel also updates live as you type, so you can watch the text change character by character.
- Use "Copy result" to put the output on your clipboard, or "Clear" to empty the box and start again.
What Is the ROT13 Cipher?
ROT13 ("rotate by 13") is a letter-substitution cipher that replaces every letter with the one 13 places further along the alphabet: A becomes N, B becomes O, and N wraps back around to A. Because the Latin alphabet has 26 letters, applying ROT13 twice returns the original text, which is why a single button encodes and decodes. Digits, spaces, punctuation, and accented characters are left untouched unless you turn on the ROT5 option, which rotates 0–9 by five places to produce what is usually called ROT18.
ROT13 is a classical cipher with no real security. There is no key and no secret — anyone who recognises the pattern can reverse it in seconds, and automated tools do it instantly. It exists to hide text from casual glances, not from attackers: spoiler warnings on forums, puzzle answers, punchlines to jokes, and obfuscated strings in CTF challenges. Never use ROT13 to protect passwords, API keys, personal data, or anything else you would mind a stranger reading.
If you need the shift to be something other than 13, the Caesar cipher tool lets you pick any shift from 1 to 25 and brute-force an unknown one. For genuine confidentiality use the AES encrypt & decrypt tool, which applies real password-based encryption, and if you only need transport-safe text rather than secrecy, the Base64 encoder and decoder is the right choice.
Frequently Asked Questions (FAQ)
How do I decode ROT13 text?
Paste the ROT13 text into the input box and apply ROT13 again. Because rotating by 13 twice adds up to a full 26-letter cycle, the second pass restores the original message — there is no separate decode button to find.
Is ROT13 the same as a Caesar cipher?
Yes, ROT13 is a Caesar cipher with the shift fixed at 13. The only thing that makes it special is that 13 is exactly half of 26, so encoding and decoding are the same operation.
What does ROT5 do to numbers?
ROT5 rotates the digits 0–9 by five places, so 0 becomes 5, 7 becomes 2, and so on. Like ROT13 it is self-inverse, and running ROT13 and ROT5 together is commonly called ROT18 or ROT13.5.
Does ROT13 work on non-English letters?
No. This translator rotates only the 26 basic Latin letters A–Z and a–z. Accented characters such as é or ü, Cyrillic, Greek, emoji, and punctuation pass through unchanged so the shape of your text stays readable.
Is ROT13 encryption, and is it secure?
It is encoding, not encryption, and it is not secure at all. ROT13 has no key, so anyone can reverse it without knowing anything about you. Treat it as a way to hide spoilers, never as a way to protect secrets.
Why is ROT13 used for spoilers and puzzle answers?
It makes text unreadable at a glance while staying trivially reversible for anyone who actually wants to look. Usenet popularised the convention decades ago and forums, puzzle sites, and comment threads still use it today.
Is the text I paste here private?
Yes. The rotation happens in your browser with plain JavaScript. ToolGenie never uploads, logs, or stores the text you enter on this page.
Tips for Working with ROT13
- Tip 1: There is no need to remember whether a string is already encoded — just run it through once and read whichever version makes sense.
- Tip 2: Leave the ROT5 box off when your text contains version numbers, dates, or IDs you still want to read; turn it on only when the numbers are part of the puzzle.
- Tip 3: ROT13 preserves length, spacing, and punctuation, so word shapes survive. Rewrite or strip formatting first if you want the output to give away less.
- Tip 4: Move up to the Caesar cipher when you need an arbitrary shift, reach for AES encryption when the data actually has to stay secret, and use the Base64 converter when you only need text that survives transport.