I worked a lot with this project, so I'd be happy to see some support for my work. The software can be downloaded from my Patreon for a  couple of bucks. Of course it's a one time payment. 

https://www.patreon.com/mateja

Not saying this is best software for these purposes, but I couldn't find any other software with the same capabilities for a reasonable price, so I think it's not a lot to ask for it. Hope you will be able to use my software, and thank you for your support in advance.

I attached some example files to help you decide whether you need this app or not. 

You can visualize the G-code files using: https://ncviewer.com