How I Built an Image Converter That Literally Cannot See Your Files

I got tired of uploading images to random converters online. Not because they were slow — though they were — but because every time I dropped a file into one of those sites, I had absolutely no idea what was happening to it on the other end. The terms of service were always three pages long and vague in exactly the right places. "We may use uploaded content to improve our services." Sure. So I built my own. And in the process, I learned that the browser is way more capable than most developers give it credit for. Here's how it works under the hood. The problem with server-side conversion Most image converter tools follow the same architecture: You upload the file to their server Their backend runs ImageMagick (or something similar) The converted file gets written to their storage You download it They delete it... probably The "probably" is the part I couldn't get past. And even setting aside the privacy angle, this approach has a real performance problem: you're bottlenecked by your up