Local · Private · Free

Caesar / ROT13 Cipher

Encode and decode Caesar, ROT13, ROT47, Atbash and A1Z26 ciphers, or crack unknown shifts with a frequency-scored brute-force panel that ranks all 25 shifts instantly.

Shift: +13

Number separatorBetween letters of a word, e.g. 8-5-12-12-15.

Word separatorBetween words. Decoding reads any digits it finds.

Preserve case Keep non-letters

This cipher is self-inverse: encoding and decoding are the same operation.

Input: 0 chars

Output: 0 chars

Everything runs on your device. Your text never leaves the browser.

Brute-force Caesar

All 25 shifts of the input, scored by English letter frequency (χ², lower is more likely English). Top 3 are highlighted. Click a row to copy its full text.

Sort by likelihood

About Caesar / ROT13 Cipher

Caesar / ROT13 Cipher is a free, private browser tool that supports Caesar, ROT13, ROT47, Atbash, and A1Z26 ciphers. It includes a frequency-scored brute-force panel that ranks all 25 Caesar shifts by their likelihood of being English. Everything runs locally on your device: no upload, no sign-up, and no installation required. It keeps working offline too. Like every free tool by Digital Heroes, it has no usage limits.

What you can do

Encrypt or decrypt text with a custom Caesar shift from -25 to +25.

Apply ROT13, ROT47, or Atbash with a single click, no configuration needed.

Encode numbers with the A1Z26 cipher using custom letter and word separators.

Crack unknown Caesar ciphers using the brute-force panel, which scores all 25 shifts by English letter frequency.

Copy or download the result as a plain-text file instantly.

Swap output back to input to chain multiple operations in one session.

How to use Caesar / ROT13 Cipher

Open Caesar / ROT13 Cipher in your browser. No signup or install needed.

Select a cipher (Caesar, ROT13, ROT47, Atbash, or A1Z26) and choose Encode or Decode.

Paste or type your text. The output updates live as you type.

For Caesar, drag the shift slider to set the shift from -25 to +25. For A1Z26, set your separators.

Check the brute-force panel below to see all 25 shifts ranked by English frequency if the shift is unknown.

Copy or download the result. Your text never leaves the browser.

Frequently asked questions

Is Caesar / ROT13 Cipher free?

Yes. Caesar / ROT13 Cipher is completely free for everyone. No sign-up, no account and no usage limits.

Is it private? Are my files uploaded anywhere?

No. Caesar / ROT13 Cipher runs entirely in your browser on your own device, so your data never leaves your computer and nothing is uploaded to a server.

Does it work offline?

Yes. This tool is a Progressive Web App. Once the page has loaded it keeps working offline, and you can install it as an app from your browser.

Do I need to install anything or create an account?

No. Just open the page and start using it. Installing it as an app is optional and only adds offline convenience.

What does Caesar / ROT13 Cipher do?

Encode and decode text with Caesar shift, ROT13, ROT47, Atbash, and A1Z26 ciphers, plus a brute-force panel that cracks unknown Caesar shifts using English letter-frequency scoring.