The desktop app uses nw.js and points that installable browser to eveeye.com.
The installation software used is Inno Setup If you do not trust the installer you can build on your own as described for Mac and Linux below.
Mac and Linux
I am sorry but i got no installer available for those platforms. If you are capable of stuff like this see the developer page.
If you can do a working package for one of those platforms i would be happy if you could provide it via github and let me know. See developer page.
Close the app
Toggle always on top mode
Window transparency slider
The desktop app is capable of reading the chatlogs written by your EVE client. See this for further explanations.