We personally stucked with a problem of cross browser compatibility and created a SaaS solution that enables to test across multiple devices simultaneously. At first we targeted QAs. But after market research we understood that we can create even better solution to make web developer's and QA's life much easier.
Currently we are working on a browser for web developers. Our core feature is that we enable developer to write code and immediately see what he has done not in one browser or device. But in many. Plus in synchronized mode. So he can scroll, click or type text in one device and see how it works on all others in real time.
Blisk browser