ROT13 Cipher
Apply a ROT13 letter-substitution cipher to rotate text characters by 13 positions.
Run tool
The ROT13 cipher tool rotates Latin letters by thirteen positions in the alphabet, providing a classic letter-substitution transformation. Because the Latin alphabet contains twenty-six letters, applying this thirteen-step rotation shifts each letter halfway through the alphabet. This symmetric structure means that running the cipher over previously rotated text returns the original message directly without requiring a separate decoding algorithm. This online transformation is commonly used in programming exercises, puzzle games, educational demonstrations, and forum posts to obscure spoilers, hints, or punchlines without hiding content behind strict access controls. Entering plain text into the input field processes uppercase and lowercase letters while preserving case structure. If the text field is empty, the tool cannot generate an output, so non-empty text must be provided. Punctuation, numerals, spaces, and special symbols pass through without modification, making it straightforward to obfuscate sentences, code snippets, or casual notes quickly.
Instructions
- Enter or paste your text into the Text input area.
- Run the cipher to rotate each alphabetical letter by 13 positions.
- View or copy the transformed text from the output area.
- To decode the message, run the rotated text through the tool a second time.
Examples
- Encoding the greeting 'Hello, World!' produces the rotated string 'Uryyb, Jbeyq!'.
- Reapplying the cipher to 'Uryyb, Jbeyq!' reverses the rotation and restores 'Hello, World!'.
FAQ
What is ROT13?
ROT13 is a simple Caesar cipher substitution that rotates letters by 13 places in the standard 26-letter Latin alphabet.
How do I decode a ROT13 message?
Because 13 is half of 26, running a ROT13-encoded string through the tool again decodes it and returns your original text.
Are numbers and symbols affected by ROT13?
No, ROT13 only shifts alphabetical letters. Numbers, punctuation marks, and whitespace remain unchanged.
Why did the tool return an error when running?
The tool requires non-empty text to generate a result. Ensure you have entered text into the input field before running.