ROT13 Encoder
Free online rot13 encoder. No sign-up, no installation. Runs entirely in your browser.
Character Map
Spoiler Mode
Encode your text and share it as a hidden message:
What is ROT13?
ROT13 is a simple letter substitution cipher that replaces a letter with the 13th letter after it in the alphabet. Since there are 26 letters in the English alphabet, ROT13 is its own inverse—applying it twice returns the original text.
ROT13 has been used historically on bulletin board systems, forums, and mailing lists to obscure sensitive content like spoilers or offensive humor from casual reading.
How to Use
- Paste or type your text into the input field
- Select a cipher type (ROT13, ROT5, ROT18, or ROT47)
- Click "Encode" to encrypt or decrypt your text
- Copy the result to your clipboard with the "Copy" button
- Use Spoiler Mode to create hidden messages for forums or messages
Common Use Cases
- Spoiler Protection: Hide movie or game spoilers on forums
- Joke Obfuscation: Hide potentially offensive jokes or punchlines
- Simple Obfuscation: Quick, reversible text encoding for casual purposes
- Cryptography Learning: Understand basic cipher concepts
- Text Processing: Test character transformation algorithms
Is ROT13 Secure?
No. ROT13 is not secure and should never be used for sensitive data. It provides only obfuscation, not encryption. Anyone can easily decode it in seconds. For actual security, use proper encryption algorithms like AES.
What's the Difference Between ROT13 and ROT5?
ROT13 rotates letters by 13 positions. ROT5 rotates only digits by 5 positions. ROT18 combines both—rotating letters by 13 and digits by 5 in a single pass.
What is ROT47?
ROT47 rotates all 94 printable ASCII characters by 47 positions. It's more comprehensive than ROT13 since it includes digits, punctuation, and special characters, not just letters.
Can I Use This Offline?
Yes! This tool runs entirely in your browser. Once the page loads, you can disconnect from the internet and continue encoding and decoding without any issues.
How Do I Decode ROT13 Text?
Simply paste the encoded text and click "Encode" again. ROT13 is symmetric—encoding an already-encoded message returns the original text.
Can I Use Different Rotation Values?
This tool provides standard rotation ciphers (ROT13, ROT5, ROT18, ROT47). If you need custom rotation values, you'll need a more advanced cryptography tool or custom code.