File extensions · Video files · Published
How to open WEBM files on Windows
A WEBM file is a video or audio file in the WebM format, an open, royalty-free format designed for the web. The WebM Project describes it as a subset of Matroska: the container is the same as MKV, but only a few web codecs are allowed inside. You usually get WEBM files by saving a video from a website, downloading from YouTube with a tool such as Parabolic, recording a screen clip in the browser, or receiving a short animation that used to be a GIF.
Because the codec list is short, a WebM file is easier to predict than an MKV. The WebM guidelines name VP8 or VP9 for video and Opus or Vorbis for audio. AV1 video also turns up in WebM files: the Matroska specification for storing AV1 states that it applies equally to WebM, although the WebM guidelines themselves have not added it. On Windows the only question is whether the decoder for that video codec is present.
.webm at a glance
- Full name
- WebM (from the WebM Project, sponsored by Google)
- Type
- Container, a restricted subset of Matroska
- MIME type
- video/webm, or audio/webm for sound only
- Video codecs
- VP8 or VP9 in the WebM guidelines; AV1 through the Matroska AV1 mapping
- Audio codecs
- Opus or Vorbis
- Opens in Windows 11 by default
- VP8 yes; VP9 and AV1 need free Microsoft Store extensions
How to open WEBM files on Windows 11
There are three free routes, from the one already on your PC to the most reliable:
- Drag the file into Edge, Chrome or Firefox. Every current browser plays WebM, because that is what it was made for. This is the fastest way to check a single clip, but you get no playlist and only basic controls.
- Open it in the Windows 11 Media Player. Microsoft lists VP8 among the codecs included with Windows. VP9 and AV1 video need the VP9 Video Extension and AV1 Video Extension from the Microsoft Store; if you hear sound but see no picture, one of these is missing.
- Install VLC or MPC-HC. Both carry their own VP8, VP9, AV1, Opus and Vorbis decoders, so nothing else is needed and the file plays the same on every PC.
To make WEBM files open in your chosen player by double-click, right-click one, choose Open with, then Choose another app, select the player and tick Always use this app to open .webm files.
| Byte offset | Bytes | What it means |
|---|---|---|
| 0 | 1A 45 DF A3 | EBML header, the same first bytes as MKV. |
| within the first ~40 bytes | 42 82 + "webm" | DocType element. This word is what separates WebM from MKV. |
How to check what a WEBM file really is
WebM and MKV start with the same four bytes, 1A 45 DF A3, and differ only in a short text field called DocType: webm or matroska. If a WEBM file refuses to open anywhere, look at it in a hex editor such as HxD or run it through the file type checker: a download that is really an HTML error page or an MP4 with the wrong extension is common.
MediaInfo shows the codecs: VP8, VP9 or AV1 for video and Opus or Vorbis for audio. That tells you which Microsoft Store extension, if any, the file needs. A WEBM with only an Opus or Vorbis track and no video is simply a music or voice recording.
Can you convert WEBM to MP4?
Yes, but unlike MKV it almost always means re-encoding. MP4 players expect H.264 or HEVC video and AAC audio, and WebM files never contain those. Converting to H.264 and AAC gives a file that plays on any phone, TV and editor.
HandBrake is the easiest free choice: open the WEBM, pick a preset such as Fast 1080p30, keep MP4 as the format and click Start Encode. Shutter Encoder and FFmpeg do the same with more control; the basic FFmpeg command is ffmpeg -i input.webm -c:v libx264 -c:a aac output.mp4.
Re-encoding costs time and a little quality. If you only need the sound, convert to MP3 or keep the Opus audio, which is already efficient. If you need the video to stay WebM for a website, trim it with LosslessCut instead of converting.
Limitations of WEBM
Many video editors and older programs do not import WebM, and hardware decoding of VP9 and AV1 depends on the device, so older phones and TVs may refuse the file or play it with dropped frames. If you are sending a clip to someone who will edit or play it outside a browser, MP4 is the safer format.
WebM does not support the subtitle and chapter variety of MKV. The WebM guidelines allow WebVTT text tracks, and most downloaded WebM files have no subtitles at all, so subtitles from YouTube usually come as a separate .vtt or .srt file.
Free programs that open .webm files
-
VLC media player Media Player
Plays VP8, VP9 and AV1 WebM with its own decoders, no Store extensions needed.
-
MPC-HC Media Player
Fast, light player with built-in LAV decoders for WebM and every other common format.
-
HandBrake Video Converter
Converts WebM to MP4 (H.264 or HEVC with AAC) for phones, TVs and editors.
-
Shutter Encoder Video Converter
FFmpeg-based converter for WebM to MP4, MP3 or editing codecs, with lossless cutting.
-
MediaInfo Media File Analyzer
Shows whether a WebM uses VP8, VP9 or AV1 and which audio codec it carries.
Free browser tools for .webm files
These tools run in your browser. Files are processed on your own computer and are not uploaded.
Frequently asked questions
Can Windows 11 play WEBM files without extra software?
Yes, in any current browser, and in Media Player for VP8 video. VP9 and AV1 WebM files need the VP9 and AV1 video extensions from the Microsoft Store, or a player such as VLC that has its own decoders.
Is WEBM the same as MKV?
WebM uses the Matroska container, the same as MKV, but allows only a few web codecs: VP8 or VP9 video (AV1 in practice too), Opus or Vorbis audio and WebVTT subtitles. MKV players open WebM files, but most MKV files are not valid WebM.
Does converting WEBM to MP4 lose quality?
A little, because the video has to be re-encoded from VP9 or AV1 to H.264. At HandBrake's default quality the difference is hard to see, but the MP4 is often larger than the WebM.
Why is my WEBM file only sound?
Either the file is an audio-only WebM, often Opus audio from a music download, or the video codec is missing. MediaInfo tells you which: if it lists a VP9 or AV1 video track, install the matching Microsoft Store extension or use VLC.
Sources
- WebM Project FAQ
- WebM container guidelines
- Matroska: AV1 codec mapping in Matroska/WebM
- Microsoft Support: Codecs in Media Player
ExeDepot does not host installers. Download buttons open each developer's own server or official download page; the links were checked on .