ROT13 Cipher — Encode & Decode Text
Encode and decode text with ROT13 cipher online. Free ROT13 encoder/decoder — symmetric cipher, encoding and decoding are identical.
Three steps to get started
Enter your text
Type or paste the text you want to encode or decode with ROT13.
ROT13 is applied instantly
Each letter is shifted 13 positions. The result appears immediately below.
Copy the result
Click Copy — the same button encodes or decodes since ROT13 is self-inverse.
ROT13: the self-inverting cipher
ROT13 is a simple substitution cipher that replaces each letter with the letter 13 places after it in the alphabet. It's named after "Rotate by 13". Because the English alphabet has exactly 26 letters, applying ROT13 twice always returns the original text — making it uniquely self-inverting.
The cipher only affects letters — numbers, punctuation, spaces, and non-ASCII characters pass through unchanged. A → N, B → O, Z → M, and so on.
Historical and modern uses of ROT13:
- Usenet: hiding spoilers so readers must actively decode
- Puzzles: light obfuscation in recreational cryptography
- Testing: verifying text processing pipelines handle encoding
- Learning: understanding the Caesar cipher family
ROT13 is a specific instance of the broader Caesar cipher family, where any shift value (1–25) can be used. The special property of ROT13 — that 13 + 13 = 26 — is what makes encoding and decoding identical operations. If you need a different shift value, use our Caesar Cipher tool.