`fswin` is a native Node.js add‑on that exposes Windows‑specific filesystem functions (such as setting file attributes, retrieving long paths, etc.) to JavaScript code. It ships pre‑compiled binaries for Node, Electron and NW.js on all Windows architectures and can be built from source with node‑gyp, making it useful for developers who need low‑level Windows file‑system capabilities in their Node applications.