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ROT13 Cipher

Conversion

Apply ROT13 substitution cipher to encode or decode text instantly in your browser.

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ROT13 Cipher
Plain text
ROT13 encoded

ROT13 has a neat property most substitution ciphers don't: applying it twice returns the exact original text, since shifting every letter forward by thirteen places and then doing it again moves each letter a full twenty-six places, all the way around the alphabet back to where it started, which is why the same operation both encodes and decodes with no separate reverse step needed. This tool applies ROT13 to text instantly, useful for the format's actual common purpose, obscuring a spoiler or a punchline in a forum post so it's not immediately visible but can be decoded on purpose by anyone who wants to read it, not real security in any meaningful sense.

See more about the ROT13 Cipher

Useful for hiding a spoiler in a post so readers can choose whether to reveal it, decoding a ROT13-obscured message back into plain text, or applying the same operation either direction since encoding and decoding are identical.

Key features

  • Clean interface
  • Fast processing
  • No signup required
  • Works offline

Quick answers for ROT13 Cipher

Why is there both an Encode and Decode mode if ROT13 is symmetric?
Mathematically running ROT13 twice returns the original text either way, but the two mode buttons are kept separate so decode mode explicitly reverses whatever you last encoded, matching how people expect an encoder/decoder pair to work.
Does it update as I type, or do I need to click a button?
The output recalculates on every keystroke, there's no separate Convert button, and a short explanation of how ROT13 works appears underneath the result.
What happens to numbers and punctuation?
Only the 26 letters, upper and lower case, get shifted, digits, spaces, and punctuation pass through unchanged.