It's funny how my experience is exactly reverse. Since I joined startup I learn much less, since we can't afford experimentation and there are no other front end devs here, so I don't get a chance to learn backend stuff, since someone has to do front end part.
I also hoped to learn some business stuff, but most of it happens behind closed doors between founders and investors while you code boring crud application.
I also hoped to learn some business stuff, but most of it happens behind closed doors between founders and investors while you code boring crud application.