Most money does still go towards developers. If I remember correctly, something like $230 million. As the other guy said, they publish their financial reports (with about a two year delay), so you can find that in there.

Besides that, a few things to consider:

* Mozilla is currently doing financially well, no one ever claimed otherwise. They are putting money to the side and also diversifying their income strategies, in case their market share falls even lower and revenue from search engines drops out. * They are still by far the smallest of the big browser vendors. Google, Microsoft and Apple could all easily invest far more money than that, if they wanted to. * Mozilla is currently developing two browser engines in parallel, implementing a new extension model, making Firefox multi-process capable and just in general dealing with a lot of technical debt. No way to truly know what Google, Microsoft and Apple are up to, but I can hardly imagine them currently doing more than Mozilla in terms of innovation and development.

All sorts of people do, since Mozilla's financials are publicly available. See the audited statement at the end of https://www.mozilla.org/en-US/foundation/annualreport/2015/

I don't know why you think this is astonishing. Google spends way more than that on Chrome, for what it's worth.

Anyway, $400 million a year, if you spend it all on developers (salaries, payroll taxes, benefits, desks, monitors, etc) gets you at most 2000 people in the US. And that's if you really stretch things, honestly.

That assumes you don't need a continuous integration infrastructure (which is actually a pretty large cost in practice). And that you don't need legal, payroll, marketing. Or any project management or management at all. And that you're not doing any documentation or anything like that.

In practice, Mozilla has a bit over 1000 employees and isn't spending all its revenue (so pays taxes on whatever it doesn't spend, and saves what's left).