Neutralinojs is a cross-platform desktop application framework that enables building native desktop apps using web technologies (HTML, CSS, JavaScript) without bundling a full browser engine. The core is a C++ binary that embeds a WebSocket server, a static file server, and a native API layer. Applications communicate with the backend via JSON-RPC over WebSocket, allowing access to OS-level features like file system, process management, clipboard, system info, and window control. The framework supports multiple deployment modes: window (native webview), browser, cloud, and chrome. The architecture is modular, with API controllers in `api/` (e.g., `app`, `fs`, `os`, `net`, `storage`, `clipboard`, `computer`) that each expose a set of methods. The server (`server/neuserver`) routes incoming WebSocket messages to the appropriate controller based on a method prefix. Authentication is handled via a token-based system (`auth/authbasic`), and permissions are enforced through allow/block lists (`auth/permission`). Extensions can be loaded as separate processes (`extensions_loader`), communicating via WebSocket with a shared token. The framework relies heavily on vendored third-party libraries: Asio for async I/O, WebSocket++ for WebSocket protocol, mbedTLS for TLS/crypto, and platform-specific libraries for hardware info, file watching, and clipboard. The build system uses CMake with platform-specific toolchains. The project includes a test suite using Mocha and a custom runner that launches the binary and executes JavaScript specs.