85 · Text Tools

Caesar Cipher & ROT13

Shift every letter by a fixed number of places to make, or solve, a simple secret message.

Mode

13 is ROT13, which undoes itself.

How to use the caesar cipher & rot13

  1. Choose encode or decode.
  2. Set the shift (13 for ROT13).
  3. Type your message and copy the result.

How it works

Each letter moves a fixed number of places along the alphabet, wrapping from Z to A. With a shift of 3, A becomes D and Z becomes C. ROT13 uses 13, so applying it twice gives back the original. It’s a puzzle, not real security.

Examples

Meet me at the old oak tree (ROT13)

Zrrg zr ng gur byq bnx gerr

Hello, shift 3

Khoor

Questions

Is this secure?

No. There are only 25 possible shifts, so anyone can try them all. Use it for puzzles and games.

How do I crack an unknown shift?

Choose decode and try shifts from 1 to 25 until the text reads normally.