MP4 to WebM
Convert MP4 video to WebM without uploading it anywhere.
Your files stay on your device — nothing is uploaded.
How to convert MP4 to WebM
- Choose an MP4 file, or drop one onto the box.
- Pick VP8 for speed or VP9 for a smaller file.
- Choose a quality level.
- Press Convert to WebM, then download the result.
Why convert MP4 to WebM
WebM is an open, royalty-free format built for the web, and it is well supported by browsers. It often produces a smaller file than MP4 at similar quality, which is useful for a site where page weight matters. Converting MP4 to WebM here re-encodes the video with VP8 or VP9 and the audio with Vorbis or Opus, all inside your browser.
VP8 or VP9
VP8 is the older codec and encodes considerably faster, which matters a lot when the work is happening on your own machine rather than a server. VP9 compresses better, so the file comes out smaller at the same quality, but it is much slower to encode. For most jobs on this site VP8 is the sensible choice, and it is the default. Pick VP9 when the file size matters more than your time.
This is the slow one
Re-encoding video is the heaviest thing this site does, because every frame has to be decoded and encoded again locally. A clip of a few seconds finishes quickly. A long or high-resolution video can take several minutes and use a large amount of memory, and a phone will be far slower than a laptop. If a conversion seems stuck, it is usually just working: leave the tab open. For very large files, trimming first is often the better move.
Your file stays on your device
Nothing is uploaded. The first time you use a video tool your browser downloads a converter of about 31 MB, once, and caches it afterwards. Nothing downloads until you pick a file, and there is no size limit because there is no upload.
FAQ
How do I convert MP4 to WebM?
Choose the MP4, pick a codec and quality, and press Convert to WebM. The file is re-encoded in your browser and offered as a download.
Should I use VP8 or VP9?
VP8 encodes much faster and is the default. VP9 gives a smaller file at the same quality but takes considerably longer, which is felt more here because the work runs on your device.
Why does it take so long?
Every frame is decoded and re-encoded on your own machine instead of a server. That is the price of not uploading your video. Short clips are quick; long ones take minutes.
Is WebM smaller than MP4?
Often yes, at comparable quality, especially with VP9. The exact result depends on the source video and the quality level you choose.
Is my video uploaded?
No. It is processed entirely in your browser and never leaves your device.