I've used plenty of online file converters. Most of them upload your files to some server, process them, then (hopefully) delete them. You're trusting a stranger's backend with your documents, photos, or sensitive data. I didn't love that. So I built ConvertifyHub — a file converter that supports 150+ formats and processes everything locally, right in your browser. Your files never leave your device. Here's how I built it and what I learned along the way. The Core Idea: Client-Side Everything The whole product is built around one constraint: no file uploads, no server, no database . That means every conversion — image, document, audio, video, archive — has to happen in the browser using JavaScript and WebAssembly.…