🔄 ROT13 Encoder
Encode and decode text using ROT13 cipher. Rotates letters by 13 positions in the alphabet.
About the ROT13 Encoder
ROT13 is a special case of the Caesar cipher where letters are shifted by 13 positions. Because the English alphabet has 26 letters, applying ROT13 twice returns the original text — making the same operation work for both encoding and decoding. This tool runs entirely in your browser.
How it works
- Each letter A-M becomes N-Z, and each letter N-Z becomes A-M.
- Letter case is preserved; non-letter characters (digits, punctuation, spaces) are unchanged.
- Applying ROT13 again to the output produces the original input.
Common use cases
- Spoiler protection — Hide punchlines, movie endings, or puzzle answers in forums and email threads.
- Casual obfuscation — Make text appear as gibberish until the reader intentionally decodes it.
- Cipher learning — A simple fixed-shift cipher to introduce substitution cryptography.
- Online games and riddles — Commonly used in geocaching puzzles and alternate reality games.
Frequently asked questions
Is ROT13 secure? No. It provides no real encryption — anyone can reverse it instantly. Use it only for obscuring content from casual glance, never for protecting secrets.
Why is encode the same as decode? Because shifting by 13 twice equals shifting by 26, which wraps around the alphabet back to the original letter.
Does this tool upload my text? No. All processing happens locally in your browser. Your text never leaves your device.
Are numbers and symbols affected? No. Only the 26 letters A-Z are rotated; everything else passes through unchanged.