Offline-capable resizer
Offline Video Resizer that works on a plane
Cloud video tools fall apart the moment connectivity does. A delayed flight, a tunnel-prone train ride, a conference Wi-Fi that asks for credentials every six minutes: all of them break tools that need a round trip to a server for every operation.
Try it now
The resize tool runs the same browser-local engine described on this page.
Why this matters
This page is different because the re-encode runs in your browser. After the first page load fetches the application bundle and the FFmpeg WebAssembly binary (cached in your browser from then on), the resize step has no network dependency. You can airplane-mode the browser and the tool still works.
The same property that makes this offline-capable makes it private. There is no server to call, which means there is no server that sees your video.
What you actually get
WASM cached on first visit
The FFmpeg WebAssembly binary downloads once on the initial page load and is cached by the browser. Future visits load instantly from cache, including when offline.
No server round trip per operation
Each resize runs entirely in browser memory. There is no API call, no upload, no waiting on a queue. Network conditions do not affect the operation.
Useful on locked-down networks
Corporate networks that block uploads, captive portals that filter outbound POSTs, and rate-limited connections all still permit the resize because no outbound traffic is involved.
Travel-friendly
Planes, trains, and remote areas with patchy coverage are normal operating conditions, not failure modes. Cache the page on the ground; resize in the air.
How to resize a video offline
01 Load the page on a working connection
Visit the Resize page once while online. The browser caches the application bundle and FFmpeg WebAssembly binary.
02 Go offline
Disconnect from the network or enable airplane mode. The page remains fully functional from cache.
03 Drop your video
Drag the source file in. The browser reads it locally; no network is consulted.
04 Resize and download
Set dimensions and run the resize. The new MP4 is written to your downloads folder, all offline.
Frequently asked questions
How does offline resizing actually work?
The actual resizing code (FFmpeg compiled to WebAssembly) ships as a static asset that your browser caches after the first download. Subsequent resizing operations execute the cached WebAssembly against the video bytes in your browser memory. No network is consulted during the resize.
Do I need to do anything special to enable offline mode?
No. Once you have loaded the page once with a working connection, the assets are cached. Closing the tab and reopening it later, even without internet, loads the cached version and the tool works.
Will the offline cache expire?
It depends on your browser cache settings. By default the cache is large enough to hold the assets for weeks of normal browsing. Manual cache clears (or private-window sessions) do remove the cached assets and require a fresh online load to repopulate.
Is offline operation the same as "private"?
They are related but distinct. Offline means the operation does not need a network to complete; private means the video does not travel over any network during the operation. Both are true here because the architecture is the same.
What if the page itself is not cached when I go offline?
You will see a network error when you try to load the URL. The HTML and assets need to have been fetched at least once. The simplest workflow: load the page on Wi-Fi, then go offline.
Related Tools and Resources
Resize Video
The actual resize tool, with all platform presets.
Private Video Resizer
Same architecture, privacy framing.
Offline Video Compressor
Same architecture for compression jobs.
Video Editor, No Upload
Full editor that runs offline after first load.