WebM

Writable

video

WebM is a media file format, developed by Google based on the Extensible Binary Meta Language.

Identify it

Extensions	`.webm`
MIME types	`video/webmaudio/webm`
Signatures	`1a45dfa3` at byte 0 (WebM)
PRONOM	`fmt/573`
Wikidata	`Q309440`
Library of Congress	`fdd000518`

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Open it

AndroidOpen sourcereads and writes · Apache Software License 2.0 / GNU General Public License, version 2.0
FFmpegOpen sourcereads and writes · LGPL-2.1-or-later / GPL-2.0-or-later
Q108353872Open sourcewrites · GNU General Public License, version 3.0
Q141647665Open sourcewrites · Apache Software License 2.0 / MIT License
DokielOpen sourcereads · CeCILL / GNU General Public License, version 3.0 / GNU Lesser General Public License, version 3.0 / Mozilla Public License, version 2.0
ExifToolOpen sourcereads · Artistic License / GNU General Public License, version 1.0 or later
FlowplayerOpen sourcereads · GNU General Public License
GStreamerOpen sourcereads · GNU Library General Public License, version 2.0 or later
HandBrakeOpen sourcereads · GNU General Public License, version 2.0
Kid3Open sourcereads · GNU General Public License / GNU General Public License, version 2.0 or later
MapLibre GL JSOpen sourcereads · 3-clause BSD License
Mozilla FirefoxOpen sourcereads · Mozilla Public License, version 2.0
OpaleOpen sourcereads · CeCILL / GNU General Public License, version 3.0 / GNU Lesser General Public License, version 3.0 / Mozilla Public License, version 2.0
PhotoRecOpen sourcereads · GNU General Public License
Q141647658Open sourcereads · Apache Software License 2.0 / MIT License
Q50938515Open sourcereads · GNU Affero General Public License, version 3.0 or later
TopazeOpen sourcereads · CeCILL / GNU General Public License, version 3.0 / GNU Lesser General Public License, version 3.0 / Mozilla Public License, version 2.0
Any Video Converterreads and writes
aomencwrites
ENVIreads and writes · proprietary license
Movavi Video Editorreads and writes · proprietary license
VideoStudio X7reads and writes
EZ CD Audio Converterreads
FakeTubereads · end-user license agreement
IrfanViewreads · freeware
LiVESreads
Mapbox GL JSreads · proprietary license
Media Player (Windows 11)reads
Mp3tagreads · free license
OvenMediaEnginereads
PowerDVDreads · proprietary license
Q300915reads · freeware
TMPGEncreads
Veblrreads
VideoStudio Pro X5reads
YouTubereads · end-user license agreement
YouTube Appreads · end-user license agreement / proprietary license
YouTube Space Rioreads

Convert it

To	With	Fidelity	Command and losses
FLAC (Free Lossless Audio Codec) 1.2.1	FFmpeg	Partial	`ffmpeg -i in.webm out.flac` Audio track only: the video is dropped.
Waveform Audio	FFmpeg	Partial	`ffmpeg -i in.webm out.wav` Audio track only: the video is dropped.
Matroska 1-4	FFmpeg	Lossy	`ffmpeg -i in.webm out.mkv` Re-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container.
MPEG 1/2 Audio Layer 3	FFmpeg	Lossy	`ffmpeg -i in.webm out.mp3` Lossy audio only: the video is dropped.
MPEG-4 Part 14	FFmpeg	Lossy	`ffmpeg -i in.webm out.mp4` Re-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container.
Ogg	FFmpeg	Lossy	`ffmpeg -i in.webm out.ogg` Lossy audio only: the video is dropped.

Sources

From Converters (FFmpeg, ImageMagick, Pandoc, LibreOffice), Just Solve the File Format Problem (File Formats Wiki), PRONOM, Wikidata. Updated 2026-10-24.

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