Caesar cipher online

Caesar cipher online. Enter text, choose settings and encrypt or decrypt immediately. Learn how it works, its history, an example and its limitations.

How does the Caesar cipher work?

What is this method?

Shifts every letter by a selected number of positions in the alphabet.

How does it work step by step?

Replace each letter with its alphabet position, add the chosen shift and wrap around after Z. Decryption performs the same operation in the opposite direction.

Example and practical use

With the text “REBUS” and a shift of 3, the result is “UHEXV”. Moving every letter back three places restores the message.

How to use the tool

Choose encryption or decryption, enter a message and set the parameters required by the Caesar cipher. The result is calculated locally in your browser and can be copied or shared without sending the text to a server.

History of the cipher

The cipher is named after Julius Caesar, who used a shifted alphabet in military correspondence. Suetonius described a version with a shift of three.

Security and limitations

This tool is educational. Classical ciphers can usually be broken with frequency analysis, repetition patterns or a small search through possible keys, so they should not protect confidential information.