Offline browser video editor

Almost every 'online' video editor stops the moment your connection does, because the actual editing happens on their servers. AetherCut is the opposite: it's a Progressive Web App (PWA) whose editing and rendering run locally, so once it's loaded it keeps working with no internet at all.

That's possible because AetherCut never uploads your footage. Your clips are read straight into the browser, edited on your device, and exported with WebCodecs and ffmpeg.wasm — all locally. No round-trip to a server means no dependency on your connection while you work.

Install it once (Chrome/Edge → Install app) and AetherCut behaves like a native app in its own window, launchable offline. It's the editor for planes, trains, spotty hotel Wi-Fi, locked-down networks, and anywhere upload just isn't an option.

How does AetherCut edit video offline?

AetherCut caches its app shell and core assets on first open, then runs the interface, timeline engine, and export pipeline in your browser. Trimming, effects, and export use your device CPU and GPU, so editing and export work offline.

When you first open AetherCut, a service worker caches the app shell and core assets. After that, launching it doesn't require the network — the interface, the timeline engine, and the export pipeline all live in your browser.

Editing operations (trim, split, transitions, text, crop, color, masking) never needed a server to begin with, and export runs through ffmpeg.wasm / WebCodecs on your own CPU and GPU. So a full edit-to-export workflow completes with the network unplugged.

What features work offline in AetherCut?

The full editor works offline, including on device auto captions after the model is cached and background removal. Optional cloud AI features like AI voiceover and generated B roll need internet. Privacy Mode disables all cloud features.

Fully offline: the entire editor, plus on-device AI like auto-captions (Whisper via WebGPU, once the model is cached on first use) and background removal (MediaPipe). These run on your device, so they don't need a connection after the model file is cached.

Needs internet (and we say so clearly): the optional cloud-AI features — AI voiceover (ElevenLabs) and generated B-roll (Kling). These genuinely call a server, so they're labeled in the UI and simply won't run offline. Privacy Mode disables all of them with one toggle if you want a guaranteed-local session.

Does offline editing keep my footage private?

Yes. If AetherCut can complete editing and export offline, your media does not need to leave your device. You can disconnect from the network, confirm no traffic in DevTools, and still finish the edit.

An editor that can do its whole job offline is, by definition, one that isn't shipping your footage anywhere. Offline capability and 'your media never leaves your device' are the same property viewed from two angles.

For sensitive footage — client work under NDA, unreleased material, medical or legal video — being able to pull the plug and still finish the edit is a strong guarantee. You can literally disconnect, verify no traffic in DevTools, and export.

Install once

Open aethercut.app in Chrome, Edge, or Safari. Click the install icon in the address bar (or use 'Add to Home Screen' on iOS / Android). The editor's service worker caches the bundle + assets locally — about 4 MB total.

What works offline

• Open the editor (loads from cache).
• Drop a local video onto the timeline.
• Cut, trim, color-grade, add transitions.
• Manual subtitles + text overlays.
• Format conversion (FFmpeg.wasm runs locally).
• Export at 4K via WebCodecs or MediaRecorder.

What needs internet

• First load (to download the bundle).
• Sign-in (Google OAuth needs a round-trip).
• Auto-captions (sends audio to Whisper).
• AI Director and AI B-roll (cloud LLM calls).
• Updates to the editor itself (refresh while online to pull the latest bundle).

Use cases that actually need offline

• Editing on a flight without paying for Wi-Fi.
• Reviewing field-recorded footage on location before uploading to your editing suite back at base.
• Working on confidential footage where the organisation requires you to be air-gapped from the public internet during editing.