Sourcegraph founder here. We love it. The more developers who are using code intelligence in their tools, the better the language support will be for all the various languages and repositories out there. That's good for developers everywhere, and we (Sourcegraph) could never build it all alone.

Our master plan at https://sourcegraph.com/plan describes what we're building on top of these basic "code intelligence" primitives, to help developers in all of their dev tools (not just GitHub), in all of their workflow, and in companies that have lots of code. And just like GitHub, we let people use these things for free on open-source so they can see how useful they are.