What is the Caesar Cipher?

Attributed to Julius Caesar, it is one of the oldest known methods of cryptology. It works using a "substitution cipher" meaning the letters in the message are substituted using a shift.

How does it work?

Alice and Bob want to share a private message with each other—but they know Eve is listening. To keep their message secret, they agree to move every letter in their message by a shift. If the shift is 3 for example, "a" becomes "d" and "b" becomes "e" etc.


  • 1. Select your desired shift from the drop-down.
  • 2. Enter your message. It can have a max lenght of 280 characters.
  • 3. Click "encrypt" or "decrypt" to shift or unshift your message.

Enter your message:

Your result: