ROT13 Encoder & Decoder
Apply the symmetric ROT13 cipher to scramble or unscramble text instantly.
ROT13 shifts each letter 13 places in the alphabet — applying it twice returns the original. Often used for spoiler tags, lightweight obfuscation in Usenet and Reddit, and as a teaching example of substitution ciphers.
Common use cases
- Hide spoilers in forum posts, Reddit comments and chat messages
- Lightly obfuscate puzzle answers or trivia game solutions
- Teach simple substitution ciphers in a CS or maths classroom
- Decode ROT13 jokes hidden in source-code comments
Frequently asked questions
Is ROT13 secure?▾
No. It's a substitution cipher with a fixed shift — anyone can decode it instantly. It's used for fun and obfuscation, not security.
Why is it symmetric?▾
There are 26 letters and 13 is half of 26, so applying the shift twice cycles back to the original letter.
Does it affect digits or punctuation?▾
No — only A–Z and a–z are rotated. Numbers, spaces and symbols pass through untouched.
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