Hi there! What is https://fider.io/ built on?

Could you please explain how did you make the UI of the application very modern and startup vibe. I am really into UI like that and I have no idea how its built. this is beyond bootstrap UI, is it true?

I geniuely thought after looking at the screenshot, I would need to learn Swift and understand how apps are made in Mac to make an app to look like that.

My background is in Java and C Sharp. Looking at Microsoft UI framework, it does not look at all what you made.

Could you please show a good place to start to make and mock UI like that ? I find your work more interesting since your background appears to be backend/cloud!