Edit a video without uploading it
If your search for 'video editor no upload' brought you here, here is the literal mechanism that lets AetherCut work without uploading anything.
The 60-second proof
Open DevTools (F12). Click the Network tab. Open the editor at aethercut.app. Drop a video onto the timeline, make a cut, export. Filter the network log by Media or XHR.
The count of outbound video bytes is zero. The file you dropped is still on your hard drive; a second copy now exists in your Downloads folder. Nothing ever crossed the network.
Why most editors upload
Browser-based video processing didn't exist until WebCodecs landed in Chrome 94 and Safari 17 made FFmpeg.wasm viable. Most editors built before then took the easier engineering path: upload the file, process server-side, return an MP4. That architecture is stuck with them today.
AetherCut started from the WebCodecs / FFmpeg.wasm starting line. The editor was built to use the browser's capabilities, so the upload step was never part of the design.
Limits to be honest about
Some AI features do call our backend by design (auto-captions sends audio to Whisper, AI B-roll sends a text prompt to Sora 2). These are opt-in, individually toggled, and Privacy Mode disables all of them at once. The default state of the editor — cut, trim, color, export — uploads nothing.