Yes, the extension supports C, C++, and C#! Sourcegraph supports over 30 languages out of the box using our basic code intelligence (search based heuristics and ctags).

Check out the recent release notes: https://about.sourcegraph.com/blog/sourcegraph-3.13#basic-co... And how out of the box code intelligence works: https://docs.sourcegraph.com/user/code_intelligence/basic_co...