A few weeks ago I launched Convert to Shorts — a free browser-based tool that converts horizontal videos to YouTube Shorts format (9:16) without uploading anything to a server. I wrote about the ffmpeg.wasm + Vite setup in a previous article. The most requested feature after launch was auto captions. Captions significantly boost Shorts engagement since most people watch without sound, and manually typing captions is tedious. The challenge: how do you add free auto captions to a privacy-fir...