Caesar Cipher & ROT13
Encode and decode Caesar, ROT13, Atbash and Vigenère ciphers. Free, no sign-up, works in your browser.
🔒 100% private — processing happens in your browser. Nothing is uploaded.
How to use the Caesar cipher decoder
- Choose a cipher — Caesar with any shift, ROT13, ROT47, Atbash or Vigenère with a keyword.
- Pick encode or decode and type your text.
- Don’t know the shift? Click Try all 25 shifts — the most English-looking result is highlighted.
The Caesar cipher shifts every letter by a fixed number; ROT13 (shift 13) is used to hide spoilers and puzzle answers online. Vigenère uses a keyword for different shifts. These are fun for escape rooms, geocaching and school projects — but they are not secure encryption; use our Encrypt File tool for real secrets.