Caesar cipher encoder with custom shift
Encode text with the Caesar cipher for puzzles, classrooms and escape rooms. It is a puzzle cipher, not a security tool.
Loading the tool…
Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter text and shift.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
For each letter with index x from 0 (A) to 25 (Z): encoded = (x + shift) mod 26. Symbols and digits are left unchanged.
Example
Inputs: Shift = 3. Result: Encoded text: Khoor, Zruog!; Letters processed: 10.
Hello, World!
Khoor, Zruog!
Limits and caveats
- This is a puzzle and teaching cipher that is easy to break, so never use it to protect passwords or sensitive data.
- Only Latin letters A to Z change; Arabic letters, digits and symbols stay as they are.
Questions about this tool
What shift did Julius Caesar use?
Historical sources say he shifted letters by 3, so A became D. Here you can pick any shift from 0 to 25.
Does it keep upper and lower case?
Yes. Capitals stay capitals, lowercase stays lowercase, and spaces and punctuation stay where they were.
Why is the Caesar cipher not secure?
It has only 25 useful keys, so anyone can try them all in seconds. Use it for puzzles and learning only.