Pyodide is a port of CPython to WebAssembly/Emscripten enabling Python packages to run directly in the browser or Node.js. We will provide an overview of Pyodide's architecture, capabilities, and potential use cases before looking into building, running, and testing Python packages for the browser. We will also discuss how browser-specific optimizations, such as code splitting, tree shaking, and lazy loading could be adapted to Python to reduce package size and load time. Finally, we will mention some of the common restrictions of the browser runtime and how they can be overcome in Python packages.