How do the darlings of Silicon Valley make money? Or, do they make money at all?

I’m sure these are questions that you’ve asked yourself, while you’ve sat there pondering your idea, your business plan, and your bank balance.

Now, there’s a site has done the research for you: How do they make money?

Craigslist, Dropbox, Google, Instagram, Twitter and, even WolframAlpha make the list.

In all, 47 companies are listed in this one handy site, and at a quick glance, you see what the money-making model is.

If there is one. Yes, I’m talking about Quora and Instagram, these standouts for not having an obvious business model.