ROT13 Encoder/Decoder
Encode and decode text using ROT13, ROT5, ROT18, ROT47, Caesar cipher, or Atbash cipher. Free online tool with real-time conversion and multiple cipher options.
ROT13
Shifts each letter by 13 positions in the alphabet (A↔N, B↔O, etc.)
Encoding and decoding are the same operation (symmetric)
Multiple Ciphers
ROT13, ROT5, ROT18, ROT47, Caesar, and Atbash ciphers all in one tool.
Real-Time Conversion
Instant encoding and decoding as you type or paste text.
100% Private
Your text never leaves your computer.
About the Ciphers
ROT13 (Rotate by 13 places)
ROT13 is a simple substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet. Because there are 26 letters, ROT13 is its own inverse - applying it twice returns the original text.
Example: "HELLO" → "URYYB"
ROT5 (Rotate digits)
ROT5 applies the same concept as ROT13 but to digits only. Each digit is replaced with the digit 5 positions after it (0→5, 1→6, etc.). Letters and symbols remain unchanged.
Example: "2025" → "7570"
ROT18 (ROT13 + ROT5)
ROT18 combines ROT13 and ROT5, transforming both letters and numbers. It applies ROT13 to letters and ROT5 to digits simultaneously.
Example: "HELLO2025" → "URYYB7570"
ROT47 (All printable ASCII)
ROT47 extends the concept to all printable ASCII characters (33-126), including letters, numbers, and symbols. Each character is shifted by 47 positions in the printable ASCII range.
Example: "Hello!" → "w6==@P"
Caesar Cipher (Custom shift)
The Caesar cipher is a classic substitution cipher where each letter is shifted by a fixed number of positions (1-25). ROT13 is actually a Caesar cipher with a shift of 13. Unlike ROT13, you need to know the shift amount to decode.
Example with shift 3: "HELLO" → "KHOOR"
Atbash Cipher (Reverse alphabet)
Atbash is an ancient Hebrew cipher that reverses the alphabet (A↔Z, B↔Y, C↔X, etc.). Like ROT13, it's symmetric - applying it twice returns the original text.
Example: "HELLO" → "SVOOL"
Frequently Asked Questions
What is ROT13?
ROT13 is a simple letter substitution cipher that shifts each letter by 13 positions in the alphabet. Since there are 26 letters, applying ROT13 twice returns the original text, making it symmetric.
How do I decode ROT13 text?
ROT13 is symmetric, so encoding and decoding are the same operation. Simply paste your ROT13 text and click "Encode/Decode" to get the original text back.
What's the difference between ROT13 and Caesar cipher?
ROT13 is a specific type of Caesar cipher with a fixed shift of 13. Caesar cipher allows custom shift values from 1 to 25 positions, making it more flexible but requiring you to know the shift amount to decode.
What is ROT47?
ROT47 is an extended version that shifts all printable ASCII characters (not just letters) by 47 positions, including numbers and symbols. It's useful when you want to obscure all types of characters.
Is ROT13 encryption secure?
No, ROT13 is not secure encryption. It's a simple obfuscation technique used for spoiler prevention, puzzle games, or hiding text from casual reading. It should never be used for actual security purposes.
What happens to numbers and symbols?
In ROT13, Caesar, and Atbash ciphers, numbers and symbols remain unchanged by default. Use ROT5 for numbers only, ROT18 for both letters and numbers, or ROT47 for all printable characters including symbols.