Encode or decode ROT13 and Caesar cipher text

How it works

1. 1

   Type or paste text into the Text box.

2. 2

   Set the shift, or press Use ROT13.

3. 3

   Read the shifted text on the right.

4. 4

   Copy it.

About the Caesar/ROT13 Cipher

The Caesar cipher replaces each letter with the one a fixed number of places further along the alphabet. It offers no real security, but it is a staple of puzzles, geocaches, classrooms and forum spoilers, where ROT13 is used to hide answers. This tool shifts the letters of your text by any amount from -25 to 25 and keeps everything else unchanged.

What you can do

• Shift text forwards or backwards by -25 to 25 places with the Shift counter.
• Jump straight to ROT13 with one button.
• Keep upper and lower case as they were, wrapping from Z back to A.
• Leave digits, punctuation, spaces and accented letters untouched.

When it works best

• Hiding spoilers or puzzle answers with ROT13, which is undone by applying ROT13 again.
• Decoding a geocache clue or escape-room message by trying shifts until it reads as words.
• Demonstrating substitution ciphers and why they are easy to break in a lesson.

Things to know

• The shift is applied in your browser.
• The output refreshes when you change the shift or press the ROT13 button, so after typing new text, nudge the shift to update it.
• To decode, use the opposite shift: text shifted by 3 is restored with -3, or 23.
• Only the 26 Latin letters A to Z are shifted. It is not encryption; for hashing use the Hash Generator.

Frequently asked questions