Encode email addresses to prevent simple spam bots
Quickly decode ROT13-encoded text from online sources
Test and verify ROT13 transformations during development
Hide puzzle answers in recreational cryptography
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Frequently Asked Questions
What is the ROT13 Cipher?
The ROT13 Cipher is an online format converter that encodes and decodes text using ROT13 cipher. It runs entirely in your browser with no data sent to any server.
How does ROT13 work?
ROT13 rotates each letter 13 positions forward in the alphabet. A becomes N, B becomes O, and so on. After Z, it wraps around to A. ROT13 is its own inverse — applying it twice returns the original text, so the same function both encodes and decodes.
What characters does ROT13 affect?
ROT13 only affects Latin letters (A-Z and a-z). Digits, punctuation, spaces, and special characters remain unchanged. Non-Latin characters (Chinese, Japanese, Arabic, etc.) are passed through without modification.
Is ROT13 secure for encryption?
No. ROT13 is a simple substitution cipher with no cryptographic security. It is commonly used for obfuscating spoilers, jokes, and puzzle answers in online forums, not for protecting sensitive data. For real encryption, use AES or other modern algorithms.
What is the difference between ROT13 and ROT47?
ROT13 rotates only letters by 13 positions. ROT47 rotates a wider range of 94 printable ASCII characters by 47 positions. ROT13 is more common for text obfuscation, while ROT47 can encode a broader character set including numbers and symbols.