Introducing the Caesar Cipher Tool — Shift, ROT13, and a Live Alphabet Map

The new Caesar Cipher tool encodes and decodes the classic shift cipher — with a slider for the shift, a one-tap ROT13 toggle, and a live alphabet map that shows exactly how each letter moves.

What it does

• Encrypts and decrypts with any shift from 0 to 25.
• ROT13 in one tap — the self-inverse shift-13 cipher.
• Preserves case and leaves numbers, spaces, and punctuation untouched.
• Shows a live alphabet map, so the transformation is never a black box.

Why we built it

The Caesar cipher is where most people first meet cryptography, and seeing it work in real time makes the idea click. It’s ideal for teaching substitution ciphers, building escape-room clues, or hiding spoilers with ROT13. We kept it fully client-side, so your message never leaves your browser.

Try it

Open the Caesar Cipher tool and encode a sentence with a shift of 3. To understand the cipher’s history, why ROT13 is its own inverse, and how to break it by hand, read The Caesar Cipher and ROT13, Explained. For more letter play, try the Anagram Solver.