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.
I find this extension really helpful when exploring unfamiliar code.
Provides editor like functionality while browsing code on GitHub. Gives you context around GitHub code you wouldn't otherwise have.
Does not support all languages. Only supports Go, TypeScript, Python, and Java.