I recently helped a friend build a small tool that processes sequences from an input file and generates XML in a specific format. My friend isn’t comfortable with the command line, so a GUI was needed. The input data also had confidentiality requirements, meaning all computation had to happen locally. Normally I’d build a desktop app, but considering long-term maintenance, I wanted to try an offline-capable PWA. I checked and found that Pyodide already ships pandas as a wasm package, so there was nothing extra to do on the runtime side — let’s go!