Text Tools

How to Use the Caesar Cipher & ROT13

2026-11-134 min readBy Apex Tool Station Team

Encrypt and decrypt messages with the Caesar shift cipher, including ROT13 and a brute-force decoder.

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1. What is the Caesar Cipher & ROT13?

The Caesar cipher shifts each letter by a fixed number of places in the alphabet — with a shift of 3, A becomes D. ROT13 (shift 13) is its own inverse and is used online to hide spoilers. Use “Show all 25 shifts” to crack an unknown Caesar message. Not secure for real secrets — use the AES text encryption tool for that.

2. How to use the Caesar Cipher & ROT13

Here is the whole process, step by step. It takes less than a minute from opening the tool to seeing your result.

1Fill in the Shift, Input fields.
2Copy or download your result with the buttons under the output.

Press the "ROT13" button and your result appears on the page.

Everything runs in your browser — your files and text never leave your device.

3. What you can do with it

Run the tool with the "ROT13" button when your input is ready.
Save your result with the "Copy" button under the tool.

4. Tips for best results

Your text never leaves your device — The tool runs entirely in your browser using JavaScript. Nothing is uploaded, so you can paste private documents without worry. That also means there is no account to create and no file to upload.
It works on your phone too — Open the tool in any modern browser on Android or iPhone. The layout adjusts to the screen and everything works the same way on a small screen as on a desktop.
Save your result before you leave — Use the "Copy" button to keep a copy.