Caesar Cipher Encoder
Encode and decode Caesar shift ciphers and ROT13, with a brute-force view of all 25 shifts.
Brute force — all 25 shifts
About this tool
Encode and decode Caesar ciphers — the classic shift substitution where each letter moves a fixed number of places along the alphabet. Set any shift from 0 to 25, or use the ROT13 and ROT47 buttons for the two common fixed rotations. When you're trying to crack an unknown message, open the brute-force panel to see the text at every possible shift at once and spot the readable one. Letters keep their case; digits, spaces, and punctuation pass through untouched.
Frequently asked questions
- Is a Caesar cipher secure?
- Not at all. There are only 25 useful shifts, so anyone can break it by trying them all — which is exactly what the brute-force panel does. It's a puzzle and teaching tool, not real encryption.
- What is ROT13?
- A Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying it twice returns the original text, so the same operation both encodes and decodes.
- What does ROT47 cover?
- ROT47 rotates the 94 visible ASCII characters (including digits and punctuation) by 47 places, so it scrambles more than just letters. It's also its own inverse.