Free tool
Caesar Cipher Converter — Encode & Decode with Any Shift
Encode or decode a Caesar cipher with any shift from −25 to +25.
Shifts each letter through the alphabet. Case is preserved; numbers, spaces and punctuation are left unchanged. A Caesar cipher is a puzzle, not real encryption. Runs 100% in your browser. Nothing you type is sent anywhere.
What the Caesar cipher converter does
A Caesar cipher shifts every letter a fixed number of places along the alphabet. With a shift of 3, A becomes D, B becomes E, and Z wraps round to C. This tool encodes or decodes with any shift from −25 to +25, keeps upper and lower case, and leaves numbers, spaces and punctuation unchanged.
How to use it
- Choose Encode or Decode.
- Set the Shift with the slider. The default is 3.
- Type your text and click Convert. Changing the shift or mode updates the result straight away.
- Use Copy or Clear as needed.
Worked examples
Encode, shift 3: Hello, World! → Khoor, Zruog!. Decoding Khoor, Zruog! with shift 3 gives back Hello, World!.
ROT13 (shift 13): abc → nop. Applying ROT13 twice returns the original text, because 13 + 13 = 26.
FAQ
Is a Caesar cipher secure?
No. There are only 25 useful shifts, so anyone can try them all in seconds. Treat it as a puzzle or teaching tool, not real encryption.
What does a negative shift do?
It shifts letters backwards. Encoding with −3 gives the same result as decoding with +3.
What happens to numbers and punctuation?
They are left as they are. Only the letters A–Z and a–z are shifted.
Is my text sent anywhere?
No. Everything runs in your browser.
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