Video

What is a WebM file?

Updated Jul 2026

Definition

WebM is an open video format built for streaming and playing directly in web browsers. It uses efficient compression to keep file sizes small while still looking sharp, which is why so much web video, from screen recordings to short clips, ends up in this format. The catch is that it doesn't play natively everywhere outside a browser.

WebMWebM video

Extension: .webm
Type: Video
Typically: Web video
Compression: Lossy

Why WebM exists

WebM was developed by Google as a royalty-free video format for the web, built around a Matroska-style container holding video compressed with VP8, VP9, or newer AV1 encoding, alongside Vorbis or Opus audio. It was designed so browsers could stream video without licensing fees getting in the way.

In practice, that makes WebM a natural fit for anything that plays inside a browser tab: embedded video players, screen recording tools, animated stickers in chat apps, and short clips shared online. The compression is efficient, so a WebM file often looks about as good as an MP4 at a noticeably smaller size.

People run into WebM most often after downloading or saving something from a website, a screen recorder, or a messaging app, then finding it won't open in a video editor, won't play on a TV or older phone, or won't attach to a document the way an MP4 would. That's usually the moment a conversion is needed.

The trade-offs

Strengths

Small file sizes without much loss in visible quality
Built for smooth playback and streaming in browsers
Supports transparency, useful for animated overlays and stickers
Free to use with no licensing costs behind the format

Watch-outs

Doesn't play natively on many TVs, older phones, and some apps
Many video editors and older software can't open it directly
Less universally supported than MP4 outside the browser
Quality is lossy, so repeated re-encoding degrades it further

A note on privacy

A WebM file itself usually carries little more than basic technical metadata, but the video content inside it can still show plenty, including locations, faces, and conversations. Uploading it to an online converter sends that footage to someone else's server before you get a file back. Converting it on your own computer means the video never leaves your machine.

Convert a WebM file

Questions

How do I open a WebM file?

Most web browsers, including Chrome, Firefox, and Edge, play WebM files directly. Outside a browser, many media players and older editing tools won't open it without converting it to MP4 first.

Is WebM better than MP4?

For web streaming, WebM often produces smaller files at similar quality. For compatibility, MP4 wins by a wide margin, since it plays almost everywhere, including phones, TVs, and most editing software.

Why did my screen recording or download save as WebM?

Many browsers, screen recorders, and messaging apps default to WebM because it's efficient and built for the web. If you need to edit or share the file elsewhere, you'll usually want to convert it first.

Can I convert WebM without uploading it anywhere?

Yes. A desktop app like Morphjet converts WebM to MP4 or other formats right on your own computer, so the footage never gets sent to an outside server.

Why won't my WebM file play on my phone or TV?

Many phones and TVs, along with iPhones by default, don't support WebM playback out of the box. Converting the file to MP4 usually solves it.

Morphjet opens and converts WebM and 1,800+ other formats, all on your own computer. Launching this July.