No upload, 100% local, no account

Video converter

Pick a target container and codec, then convert in your browser. Your file never leaves your device.

How Video converter works

Video converter changes a clip from one container/codec to another, MP4, WebM, MKV or MOV, with H.264, H.265 or VP9 video. Unlike a size-focused compressor, you choose the exact output format, which is handy for compatibility (e.g. MP4/H.264 plays everywhere) or for the web (WebM/VP9). Drop a file, pick the container and codec, and download the result.

It runs through ffmpeg compiled to WebAssembly. Converting between codecs always re-encodes the video, so it can be slow, H.265 and VP9 are especially heavy. No account, no watermark.

Frequently asked questions

Are my files uploaded to a server?

No. ffmpeg compiled to WebAssembly converts your video in this browser tab, it is read into memory on your own device and re-encoded there to the container and codec you pick (libx264, libx265 or libvpx-vp9 for video; aac or libopus for audio), and the result is offered as a local download. Nothing reaches Sunasty or any third party. Open your browser's DevTools, go to the Network tab and watch: no request carries your video.

Which formats and codecs are supported?

Containers: MP4, WebM, MKV and MOV. Codecs: H.264 (AVC), H.265 (HEVC) and VP9. Only valid combinations are offered, for example WebM uses VP9 video with Opus audio, while MP4/MOV use H.264 or H.265 with AAC.

Why is conversion slow?

Changing codec means decoding every frame and re-encoding it. That is CPU-intensive, and doing it with WebAssembly in a browser tab is slower than a native app. H.265 and VP9 are the heaviest; H.264 is the fastest. Smaller/shorter clips convert much quicker.

Does it work offline?

Yes, once the page has loaded. Because the processing happens on your device, you can disconnect from the network and the tool keeps working. This is the clearest proof that your data never leaves your machine.

Is it free? Do I need an account?

It is completely free and requires no sign-up. There are no watermarks, no daily limits and no tracking cookies needed to use the tool.