The next project that we are coding in, we are making the UI flat, can anyone suggest some good fonts that would look good with it and which are freely available.
I like the "
Lato" font family. Maybe a few more like this?
So the Lato font family is what's known as a 'sans-serif' font. If you like it, you should probably look for other sans-serif fonts. The most classic/timeless/respected font would be Helvetica, but its licensing is expensive. A couple free alternatives:
Open Sans: Essentially open-source Helvetica. Always a good choice.
Source Sans Pro: Adobe's take on an open-source modern sans-serif.
Roboto: Google's sans-serif of choice for the Android operating system.
And you can find these and a bunch more free google webfonts here, on a curated list by SOMA design. Its a good starting point, if nothing else.
Quick (opinionated) sidenote: A 'flat' design does not inherently have fonts that go well with it or not. Don't limit yourself to whatever FlatUI Pro does - use the toolkit as a starting off point to find your own (or your company/client's own) style. Going a completely different direction with the primary display font can easily achieve that - play around. Typography is a vast world of artistic directions, and there's rarely one correct answer.