ROT13 is a Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying ROT13 twice returns the original text, so the same action both encodes and decodes.

Is this secure encryption?

No. A Caesar cipher is a simple letter-shift suitable for puzzles, obfuscating spoilers, or learning — not for protecting sensitive data.

ROT13 / Caesar Cipher

Encode and decode text with a Caesar shift cipher, including the classic ROT13. Choose any shift from 0 to 25, switch between encode and decode, and watch the result update live — letters keep their case and everything else passes through unchanged.

How to use ROT13 / Caesar Cipher

Enter your text and pick a shift (or click ROT13).
Choose Encode or Decode.
Copy the transformed text.

Frequently asked questions

What is ROT13?: ROT13 is a Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying ROT13 twice returns the original text, so the same action both encodes and decodes.
Is this secure encryption?: No. A Caesar cipher is a simple letter-shift suitable for puzzles, obfuscating spoilers, or learning — not for protecting sensitive data.

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