Text Tools

ROT13 & Caesar Cipher

Encode and decode text using ROT13 or any Caesar cipher shift (1–25). Works on letters only, preserves case.

Runs in your browser

Input
Output
Characters:
Letters shifted:
Shift:

Alphabet Mapping (shift = )

A–M
N–Z

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What is the Rot13 Cipher?

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. Because the English alphabet has 26 letters, applying ROT13 twice returns the original text, making encoding and decoding the same operation. It is commonly used in online forums and puzzle communities to hide spoilers or punchlines without true encryption.

How to use the Rot13 Cipher

  1. Type or paste the text you want to encode or decode into the input field.
  2. The output updates in real time - ROT13 is applied immediately as you type.
  3. Because ROT13 is its own inverse, the same operation encodes and decodes. Paste encoded ROT13 text into the input to reveal the original.
  4. Numbers, punctuation, and spaces are passed through unchanged.
  5. Click Copy to copy the result to your clipboard.

Frequently asked questions

No. ROT13 provides zero security - it is trivially reversible and was never intended as encryption. It is only useful for obscuring text from casual view, such as hiding spoilers.
No. ROT13 preserves case: uppercase letters rotate within A - Z, and lowercase letters rotate within a - z. The output case matches the input case.
ROT47 is a variant of ROT13 that also rotates digits and punctuation characters, operating on the 94 printable ASCII characters (codes 33 - 126). It is useful when you also want to obfuscate numbers and symbols.