What is understand-open-source?

understand-open-source is a skill for Claude Code, Anthropic's coding assistant, that is meant to give you a genuinely deep understanding of an open source project rather than just a surface level summary from its README. The idea behind it is that most people learn what a library does by skimming its documentation, but this tool instead goes and reads the project's actual source code. Running it starts with a tool called opensrc, which downloads the real implementation files for an npm, PyPI, or GitHub hosted project, not just its docs. From there, a second tool called graphify builds a graph showing how the different pieces of code in that project connect to each other. That graph is used to spot the parts of the codebase that matter most, the central pieces many other parts depend on, so that Claude does not have to read every single file to understand the project. Once the important files are identified, Claude reads those specific files and writes up an explanation of how the project actually works, covering its overall architecture, the core abstractions with real code snippets pulled from the source, an end to end trace of how something flows through the system, and pointers on where someone might start if they wanted to contribute. The output is a shareable HTML report you can open in any browser, generated from a single command like slash understand-open-source zod, which in that example would explain the popular zod library by tracing through its actual parser and type checking code. Using it requires installing two separate tools first, opensrc and graphify, then placing the skill's file into your Claude Code skills folder. It is aimed at developers who want a real, code level understanding of a dependency or open source project they are relying on.