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ROT13 Encoder Decoder - Free Online ROT13 Cipher Tool

Encode or decode text using the rot13 cipher algorithm with this free online tool. This simple letter substitution cipher performs rot13 encryption and decryption using the same operation. Fast, instant rot13 encoder and decoder that runs entirely in your browser.

💡 ROT13 对称加密（编码=解码）

How to Use ROT13 Encoder Decoder

Quick Start Guide

1

Enter the text you want to encode or decode in the input box

2

Click 'ROT13 Convert' button to apply the ROT13 cipher

3

The output shows the encoded/decoded result instantly

4

Use 'Copy' button to copy the result, or 'Clear' to start over

💡Pro Tips

✓ROT13 is a symmetric cipher - encoding and decoding use the same operation
✓Only letters (A-Z, a-z) are transformed; numbers and symbols remain unchanged
✓Commonly used for hiding spoilers in online forums and newsgroups
✓All processing happens locally in your browser - no data sent to server

Frequently Asked Questions

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. It's a special case of the Caesar cipher developed in ancient Rome.
Because the English alphabet has 26 letters and 26 = 2 × 13, applying ROT13 twice returns the original text. This means the same operation works for both encoding and decoding.
No, ROT13 provides virtually no cryptographic security. It can be easily broken by anyone who knows it's being used. It's only suitable for hiding text from casual observation, not for protecting sensitive information.
ROT13 only transforms uppercase (A-Z) and lowercase (a-z) letters. Numbers, punctuation, spaces, and other special characters remain unchanged.
ROT13 is popular in online forums, Usenet newsgroups, and puzzle games to hide spoilers, punchlines, puzzle solutions, or offensive material from immediate view while keeping it easily accessible to those who want to see it.

Still have questions? Check out our other tools or contact us for support.

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