WebM compressor
Make a WebM smaller, whether it came from OBS, a screen recorder or a download. Keep it as WebM (VP9) or turn it into a universally playable MP4.
What is a WebM file?
WebM is an open container from Google based on Matroska. It carries VP8, VP9 or AV1 video with Opus or Vorbis audio, and plays in all major browsers.
Why WebM files get big, and how this shrinks them
Browser screen recorders often save WebM at high, variable bitrates. Re-encoding at a fixed target bitrate brings the size under control.
Tips for WebM
- Choose VP9 in the codec menu to keep a .webm output (if your browser can encode VP9).
- Choose H.264 for an MP4 that plays in iPhone Photos, Windows and most editors.
- Sound in WebM output is Opus; in MP4 output it is AAC.
Need an exact size? Try 20 MB, 25 MB or the bitrate calculator.
Other formats
Questions people ask
Should I keep WebM or convert to MP4?
Keep WebM for websites and Chrome/Firefox playback. Convert to MP4 (H.264) if the file is going to phones, editors or people whose devices you don't know.
Does Discord play WebM?
Discord embeds WebM in most clients, but MP4 with H.264 is the safest choice for inline playback everywhere.
Why is VP9 greyed out?
The codec list only offers encoders your browser reports. If VP9 isn't available, H.264 MP4 output still works.