Most video editors upload your footage the moment you start. Your raw clips move to a server you don't control, processed by infrastructure you can't audit. AetherCut works differently — and you can verify it yourself in under 60 seconds. Here's the full technical breakdown. The Architecture: Why Nothing Leaves Your Device AetherCut runs inside a browser tab. No install. No account required to start. Every processing operation — cutting, captioning, chroma key, export — executes locally using three browser APIs that have quietly made client-side video processing viable. HTML5 Canvas API The Canvas API is the rendering layer. Every frame you see in the AetherCut timeline is drawn to an off-screen canvas. Compositing, overlays, text, and visual effects are applied directly in-memory on your device. No frame data is serialized and sent over the wire. WebCodecs API — H.264 Hardware-Accelerated Export The WebCodecs API is what makes 5x realtime export possible. It gives JavaScript direct access to the browser's hardware video encoder — the same H.264 acceleration your GPU uses for everything else. Before WebCodecs, browser-based video export had to go through software encoders, which were slow and CPU-heavy. WebCodecs bypasses that entirely. The practical result: a 60-second 1080p clip exports in roughly 10–12 seconds on a mid-range machine. The encoded output never touches a server — it writes directly to your local filesystem.