ROT13 Encoder & Decoder

About this tool

Apply ROT13, a simple letter cipher that rotates each letter 13 places. Because 13 is half of 26, running ROT13 twice returns the original, so the same button encodes and decodes.

Example

Input: Hello

Output: Uryyb

Privacy

This tool runs entirely in your browser. Your data is processed locally and never uploaded to a server.

How to use this tool

1. Paste or type the text you want to change into the input box.
2. Click the ROT13 button to apply the letter shift.
3. Use the same button again if you want to switch the result back to the original text.
4. Copy the transformed text from the output area.

Step by step, what happens

1. The tool reads your text one character at a time.
2. It changes only letters, rotating each A to N, B to O, and so on for both uppercase and lowercase.
3. Non-letter characters such as spaces, numbers, punctuation, and symbols stay exactly the same.
4. Because ROT13 is its own inverse, running the tool again on the result restores the original text.

Worked example

If you enter a short note like a hidden reminder, the tool will rotate only the letters and leave the rest untouched.

Input: Hello, world!

1. The tool shifts each letter 13 places through the alphabet.
2. The comma, space, and exclamation mark are left as they are.
3. The encoded text is ready to copy or run through ROT13 again to decode.

Tips and common mistakes

• Uppercase and lowercase letters are handled separately, so the tool preserves the original case.
• If your text already looks scrambled, applying ROT13 again will return it to readable form.
• Numbers, punctuation, and spaces are not changed, so only the letters will look different.
• ROT13 is not encryption for privacy, so do not use it for secrets you need to protect.

Frequently asked questions