WebM converter video to transparent WebM, with real alpha
Turn a normal clip into a WebM with a genuine VP9 alpha channel, the background isn't a colour to key out, it's simply not there.
Upload a video of a person and download a transparent WebM that plays over any background. Free, no sign-up, no watermark. If you're wondering how to make a transparent background for a video, or how to make background transparent online without installing anything, this is it: one upload. How do I make a transparent background on a clip rather than a photo? The same way, and the steps for how to make transparent background clips stay the same: upload, wait, download, and the page hands you a video transparent background directly. The WebM keeps your original audio track (Opus) alongside the alpha channel.
Related: Convert any video to VR.
By Sam Ridder · Last updated: October 2026
No watermark on the free export. Transparent WebM, GIF or green screen, straight out: free exports go up to 1920 px.
What a transparent WebM actually is
A transparent WebM stores an alpha channel: every pixel has a see-through value, so the subject stays fully opaque while the background is literally empty. That's different from a green screen, where the background is a real green colour you still have to remove. VideoBGNinja produces the alpha for you, no keying required.
For the full rundown of where alpha WebM plays and how to use it, see the transparent video guide: this page is the quick how-to for the conversion itself.
- Real transparency, not a colour to key out
- One file that drops onto any background
- Keeps your original audio (Opus in the WebM)
- No watermark, no account
Where the WebM plays
Chrome, Edge and Firefox play VP9 alpha natively in a <video> tag, OBS accepts it as a media source for stream overlays, but editors like DaVinci Resolve, Premiere Pro and After Effects don't open a transparent WebM without a plugin. For those, and for any app that can't read alpha, use the green-screen MP4 that comes with every job instead.
- Websites,
<video>with transparency - OBS: media source for overlays (guide)
- Editors (Resolve, Premiere, After Effects): use the green-screen MP4 or the alpha matte
- Fallback: the green-screen MP4 for everything else
How to convert to a transparent WebM
The tool is tuned for short clips: up to 2 GB and 90 seconds per upload, processed at up to 1920px. Longer material? Trim it into parts first: that keeps processing fast and free for everyone. A human subject is what it does best.
- Open VideoBGNinja and upload your clip (MP4, MOV or WebM).
- The AI removes the background on our GPU and builds the alpha.
- Download the transparent WebM (VP9 alpha).
- Drop it onto any background in your browser, OBS or editor.
By Sam Ridder, I build and run VideoBGNinja on my own hardware, on my own. Who I am.
MP4 to transparent WebM: what the download contains
To turn an MP4 into a transparent WebM, upload the MP4 as it is. The AI cuts the person out frame by frame and writes the result as VP9 video with an alpha channel (yuva420p), so you get a WebM with alpha instead of a colour to key out. It is not the only file: every job also returns a green-screen MP4 and a greyscale alpha matte MP4 for editors that cannot open alpha WebM.
For a quick video to transparent background on a web page or a stream overlay, the WebM is the file to use. Looping is a player setting, not part of the file: add the loop attribute to the <video> tag, or tick Loop on the OBS media source, and the transparent WebM repeats for as long as you like. Need a GIF instead? Upload the original clip in cut-out mode, which also returns a transparent GIF of the first 10 seconds at 480 px (see video to GIF); running a finished WebM through the plain GIF mode loses the transparency.
Sources
- The WebM Project | About WebM: WebM uses VP8 or VP9 video with Vorbis or Opus audio
- Alpha compositing - Wikipedia: Alpha channel stores per-pixel transparency from 0 to 1
- Alpha transparency in Chrome video: Chrome plays WebM video with alpha transparency
Common questions
What is a VP9 alpha WebM?
A WebM video that carries a real alpha (transparency) channel, so the background is empty rather than a solid colour. It drops onto any background without keying.
Which players support it?
Chrome, Edge and Firefox play it natively, OBS reads it as a media source, while Resolve, Premiere and After Effects need a plugin for it. Use the green-screen MP4 or the alpha matte in those editors.
Does the audio survive?
Yes. Your original audio is kept in the WebM (Opus) and in the green-screen MP4 (AAC).
Is there a size limit?
Up to 2 GB and 90 seconds per clip, processed at up to 1920px.
Is there a way to get a WebM video with a transparent background?
Yes: VideoBGNinja does exactly this, free in your browser. No account, no watermark and nothing to install.
Is VideoBGNinja a webm background remover, or does it only add transparency to a file I already keyed?
It's the whole job in one pass. Upload any clip and it comes back with the background removed and the alpha channel already baked into the WebM.
Does it webm remove background automatically, or do I need to key a colour myself first?
Automatically. There's no green screen or colour to pick: the AI finds the person and cuts them out on its own.
Can I remove background from webm clips I already have, or does it only remove background webm-style from a fresh upload?
Either way. Upload your existing WebM (or any common video format) and it goes through the same background removal.
Does webm transparency survive re-encoding, and can I remove webm background from a file I already exported?
Yes to both: re-encoding a WebM with alpha keeps its webm transparent background intact as long as your tool respects the alpha channel, and you can run an already-exported clip back through to strip its background again.
Which video formats can I upload to get a transparent WebM?
You can upload MP4, MOV, WebM, MKV, AVI, M4V, MPG, MPEG, WMV or 3GP. The AI removes the background on our GPU and builds the alpha, so you get the transparent WebM back with your original audio kept in it (Opus).