Is ROT13 secure encryption?

No. ROT13 offers no security whatsoever — it is a trivially reversible substitution. Use it only for casual obfuscation such as hiding spoilers, never for protecting sensitive information.

Does ROT13 change numbers or punctuation?

No. Only the 26 Latin letters (A–Z, a–z) are shifted. Digits, spaces, punctuation, and all other characters pass through unchanged.

Is my text uploaded to a server?

No. The encoding runs entirely in your browser using JavaScript. Nothing is sent to any server.

What is the difference between encoding and decoding ROT13?

There is no difference. Because the alphabet has 26 letters and ROT13 shifts by 13, applying it twice returns the original. The same button both encodes and decodes.

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ROT13 Encoder / Decoder

Encode or decode text with the ROT13 substitution cipher instantly. Free, private, runs in your browser.

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What is ROT13?

ROT13 ("rotate by 13") is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet. Because there are 26 letters, applying ROT13 twice returns the original text — encoding and decoding are the same operation. Non-letter characters (digits, spaces, punctuation) are left unchanged.

ROT13 Substitution Table

Plain	ROT13
A B C D E F G H I J K L M	N O P Q R S T U V W X Y Z
N O P Q R S T U V W X Y Z	A B C D E F G H I J K L M

Common Uses

ROT13 is widely used on internet forums and newsgroups to hide spoilers, puzzle answers, or mildly offensive content so readers must actively choose to decode it. It is not a secure cipher — anyone who recognises it can decode it instantly — but it serves as a simple "opt-in" text obfuscation layer.

ROT13 Encoder / Decoder

What is ROT13?

ROT13 Substitution Table

Common Uses

Frequently Asked Questions