Ask HN: How do you familiarize yourself with a new codebase?
I use CodeMap[1] which is a kind of google maps but where the countries are the code, and CodeGraph[2] which helps to understand code dependencies at different granularities (package, module, files, functions).
[1] https://github.com/facebook/pfff/wiki/CodeMap
[2] https://github.com/facebook/pfff/wiki/CodeGraphdisclaimer: I am the author of those tools.