ROT13 Encoder – Encode ROT13 Online (Free Tool)
Free online ROT13 Encoder tool to encode text using ROT13 cipher. Replace each letter with the letter 13 positions after it in the alphabet. Perfect for simple text obfuscation and puzzles.
Example Output
Each letter rotated 13 places; punctuation untouched.
Uryyb, Jbeyq!
What is ROT13 Encoder?
ROT13 Encoder shifts every letter by 13 positions in the alphabet — a classic ultra-simple cipher used to hide spoilers, puzzle answers, and joke punchlines in plain text. Not encryption; just obfuscation. Useful for forum posts, classroom puzzles, and quirky URL parameters.
Why use this tool?
- Lightweight page weight that loads quickly even on slow connections
- Works on desktop, tablet, and mobile in any modern browser
- Stable behavior across visits — no surprise version drift
- No character or word-count cap on the input
- Handles Unicode correctly — emoji, CJK, Arabic, and accented Latin all stay intact
How to use
- Paste plain text
- Click Encode — each letter rotates 13 positions in the alphabet
- Copy the ROT13 result
- Apply ROT13 again to decode (it's a symmetric cipher)
Examples
Hide a movie spoiler
Encode "the killer is the butler" → "gur xvyyre vf gur ohgyre". Readers can decode with one click if they're willing to be spoiled.
Puzzle answer
Provide the answer to a puzzle in ROT13 so players have to deliberately decode to see it.
Common use cases
- Hiding spoilers in forum/chat posts
- Puzzle and ARG content
- Quirky URL parameters in casual demos
- Teaching basic substitution ciphers
Troubleshooting
- Numbers/symbols unchanged.
- By design — ROT13 only rotates letters A-Z (case preserved). Numbers and punctuation pass through untouched.
Frequently Asked Questions
ROT13 is a simple letter substitution cipher that replaces each letter with the 13th letter after it in the alphabet. It is its own inverse, meaning applying it twice returns the original text.
Try these related tools
Explore more Text Tools
Discover other free, privacy-first tools in Text Tools.