Ah yes, the Caesar Cypher, 

an Iconic cypher. known for it's appearance in the "Gravity Falls Bill Cipher Statue Hunt". 

But now,

You can use it yourself!

 ---PRE ANSWERED QUESTIONS---

What are the Advantages Of having it offline?

You don't need internet, so if you need to get something ciphered. you can do it Easily even without internet!

Is it free?

None of my software is paid (Or Choose Your Own Price), So, It's free!

What operating system do I need to run it?

You need windows.

Is it open source?

Yes, The MFA file is the source code. Open it in Clickteam Fusion 2.5 Standard. You may need to install an extension to Clickteam via the Clickteam Extension Manager.

My antivirus is flagging it.

It happens to me too, Just know, It isn't a virus.

What are you waiting for!

It's free, open source, AND OFFLINE!