Trimming Video in the Browser Without Uploading to a Server

Every time you upload a video to an online trimming service, that service has your video. For personal clips, that might be acceptable. For work content, screen recordings with sensitive data, or anything under NDA, uploading to a third party is a non-starter. Browser-based video trimming that runs entirely client-side solves this. The video never leaves your machine. No upload, no server processing, no privacy concerns. How browser-based trimming works Modern browsers have two key APIs that enable this: MediaSource API allows JavaScript to feed video data to a <video> element, enabling seeking to precise frame positions for setting trim points. FFmpeg.wasm is a WebAssembly port of FFmpeg that runs entirely in the browser. It provides the same trimming, encoding, and muxing capabilities as desktop FFmpeg, but in a sandboxed browser environment. The workflow: Load the video into memory using the File API Display it in a video player with frame-accurate seeking Let the user set sta