ROT13 Text
Encrypt or decrypt text using the ROT13 cipher. Shifts letters by 13 places in the alphabet.
Settings
Live Statistics
Continue with Related Tools
What is ROT13?
ROT13 is a simple letter substitution cipher where each letter in the text is replaced by a letter 13 positions down the alphabet. It's a variant of the famous Caesar cipher used by Julius Caesar over 2000 years ago.
For example, the text Hello World becomes Uryyb Jbeyq when ROT13 encrypted.
Features
Symmetric Cipher
No keys or passwords! The same operation encrypts and decrypts.
Batch Processing
Encrypt multiple lines at once with line-by-line mode.
File Upload
Load `.txt` or `.md` files and download encrypted results.
Instant Processing
See results in real-time as you type.
Case Preserved
Uppercase stays uppercase, lowercase stays lowercase.
Client-Side Only
All processing happens in your browser. We never see your data.
How to use
- Input: Type your message (e.g., a spoiler or puzzle answer).
- Encrypt: The tool instantly shifts letters by 13 positions.
- Decrypt: Run the encrypted text through the tool again to get the original back.
Example - Hide a Spoiler
Frequently Asked Questions
What is ROT13?
ROT13 ('rotate by 13 places') is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet. For example, 'A' becomes 'N', 'B' becomes 'O', and so on. It's a special case of the Caesar cipher invented by Julius Caesar.
How do I decrypt ROT13?
The beauty of ROT13 is that it is symmetric and self-inverse. Since the alphabet has 26 letters, shifting by 13 twice (13 + 13 = 26) brings you back to the original text. Just run the encrypted text through the tool again to decode it!
Is ROT13 secure encryption?
No, ROT13 is not secure and should never be used for sensitive data. It's trivially easy to break (just shift back 13). Use it only for obfuscation—hiding spoilers, puzzle answers, or jokes—not for protecting passwords or confidential information.
What characters does ROT13 affect?
ROT13 only affects letters (A-Z, a-z). Numbers, punctuation, spaces, emojis, and special characters are left completely unchanged. This preserves the structure and readability of the text.
Does ROT13 preserve case?
Yes! Uppercase letters remain uppercase (A → N), and lowercase letters remain lowercase (a → n). This means 'Hello World' becomes 'Uryyb Jbeyq', not 'uryyb jbeyq'.
Can I use batch mode to encrypt multiple lines?
Yes! Enable 'Batch Mode' to process each line independently. Paste a list of items (one per line), and each will be encrypted/decrypted separately while preserving the line structure.
Can I upload a file to encrypt?
Yes! Click 'Upload' to load a .txt, .md, or .csv file. The tool will encrypt the entire contents, and you can download the result as a new file.
Why is ROT13 popular on the internet?
ROT13 is widely used in forums, mailing lists, and newsgroups to hide spoilers, punchlines, or offensive content. It allows people to share text that requires a conscious effort to read, preventing accidental exposure.
Is my data sent to your server?
No. All encryption and decryption happens entirely in your browser using JavaScript. We never see, store, or transmit your text. This makes it safe to use for any content.
What is the difference between ROT13 and ROT47?
ROT13 only rotates letters (A-Z). ROT47 rotates all printable ASCII characters (including numbers, punctuation, and symbols). Use the mode toggle at the top to switch between them.