ROT13 Encoder & Decoder - Free Online Tool
What is ROT13?
ROT13 rotates each letter 13 positions in the alphabet, so A becomes N, B becomes O, and so on. Applying ROT13 twice returns the original text, making it its own inverse. Use it to hide spoilers, obscure answers, or play with classic Unix culture.
How to use the ROT13 tool
- Enter text: Paste your message, spoiler, or answer.
- Transform: Click ROT13 to encode or decode (same button for both).
- Copy output: Copy the result for forums, emails, or puzzles.
Why use ROT13?
- Self-reversing: One click encodes; another click decodes.
- Spoiler-friendly: Hide plot twists or puzzle answers in plain sight.
- Unix tradition: A classic tool with roots in Usenet and early internet culture.
Use case 1: Forum spoilers
Post ROT13 movie or game spoilers so readers choose whether to decode.
Use case 2: Puzzle answers
Hide quiz answers on the same page; users apply ROT13 to reveal.
Use case 3: Quick obfuscation
Obscure text from casual glances without serious encryption.
Examples
Basic example
Input: hello world
Output: uryyb jbeyq
Advanced example
Input: uryyb jbeyq (already ROT13)
Output: hello world (back to original)
Common errors
Expecting security
ROT13 is obfuscation, not encryption. Anyone who knows the scheme can decode instantly.
Non-letter characters
Numbers, punctuation, and symbols stay unchanged; only A–Z shift.
Tips and proven approaches
- Mention "[ROT13]" before encoded text so readers know to decode.
- Combine with the Base64 encoder for two-layer obfuscation.
- For variable shifts, use the Caesar cipher tool.
Related tools
- Shift by custom amounts with the Caesar cipher encoder.
- Convert to dots and dashes using the Morse code converter.
- Encode to ASCII-safe strings with the Base64 encoder.
Privacy and security
All encoding runs locally in your browser. ROT13 is not secure; treat it as a convenience, not protection.