Sourcegraph CEO here. Unlike GitHub, Sourcegraph actually understands the code like your IDE. Unlike your IDE, it has all the code on GitHub and some other repo hosts already loaded up and built. (We're working on adding more languages beyond Go, etc.; check https://sourcegraph.com/beta for early access.)

Try out jumping to definition and seeing hovers at https://sourcegraph.com/github.com/gorilla/mux/-/blob/mux.go.... This helps you understand code that you're browsing.

Check out global usage examples and refs of any function, such as those at https://sourcegraph.com/github.com/golang/go/-/info/GoPackag.... You can get to this page by right-clicking on tokens in the code view above. This helps you quickly figure out how to use a piece of code and see best practices.

Finally, the code search is also semantic and is ranked by popularity. Try it out at https://sourcegraph.com/search?q=new+http+request.

Code analysis and search at this scale is tough, but we're going to do it right, because it'll help developers learn more quickly, write better code, and reuse more existing stuff. (We're not totally there yet, but if you want to help by adding language support or joining our team, email me at [email protected].)