// the take
This is the open-source core of JetBrains' IDE platform — the codebase that IntelliJ IDEA, PyCharm, and the rest of the JetBrains IDE family build on. It's for plugin authors who need to read platform internals, people building their own IDE on top of the platform, or contributors fixing bugs in the actual editor/indexing/VFS layers, not for someone looking for a weekend side project.
It's genuinely the real thing — the exact platform code shipping in production IDEs used by millions, not a toy subset, with CI badges proving IntelliJ IDEA and PyCharm both build green off this tree. The modular architecture (separate platform, language plugins, Android modules as their own checkout) actually holds up as a reusable base for building other tools, which is why plugin devs rely on it as a reference. The .agents/skills and .claude/skills directories show unusual investment in making a codebase this size navigable by AI coding agents — dozens of scoped skill docs for things like bazel test migration, module dependencies, and PSI/ModCommand migration.
The build system is mid-migration to Bazel and the README says so outright: expect rough edges, and building with just the IDE's own capabilities is explicitly unsupported now. Some tests can't be run under Bazel yet and still require the legacy tests.cmd path, so you're dealing with two build systems simultaneously. Getting a working checkout isn't trivial — Android modules live in a separate repo that must stay branch-locked with this one, and Windows needs specific git config just to clone without breaking on long paths or line endings. At this scale, drive-by contribution is unrealistic; this is a codebase you commit real time to before you can touch anything beyond the edges.
We read the README, the directory tree and a key source file in October 2026. Nobody pays to be listed. How we judge →