
Sourcegraph provides IDE-like tools for GitHub to make code search, browsing and navigating code more delightful. Get multi-repo search, jump to definition, find references, and file tree navigation.
Great product with a lot of great features that can help you easily find code. The paid product is rather expensive though and I can't see a legitimate reason to use it unless your dealing with either lots of private repos or need the automations included within it, and even then its still somewhat pricey for those features.