Video tools
Convert MP4 and M4V videos into WebM files directly in your browser without uploading the file.
Your MP4 preview will appear here.
WebM quality
Browser-native WebM
This converter uses MediaRecorder, so codec support depends on your browser. Standard MP4 files are usually easiest to convert.
Upload an MP4 or M4V file, choose the range you want to convert, select an output width and quality preset, then create a WebM download.
For smaller WebM files, lower the width, choose the Small preset, reduce the frame rate, or disable audio when you do not need it.
This browser-only converter redraws the MP4 video into a canvas and records that canvas as a WebM file using MediaRecorder.
It is a practical local conversion workflow, not a lossless container remux. Quality and file size depend on the selected bitrate, width, and motion in the source.
The source video is decoded and converted locally on your device. This tool does not upload or store the MP4 file.
Conversion runs in real time, so a one minute selected range usually takes about one minute to process.
For websites, WebM can be a useful companion format next to MP4 because modern browsers can play it efficiently.
No. The conversion runs locally in your browser with video, canvas, Web Audio, and MediaRecorder APIs. Your file is not uploaded or stored by this tool.
Without FFmpeg, the browser records the selected range while playing it. That keeps the tool private, but longer videos take longer to convert.
The browser must be able to decode the MP4 codec inside the file. Standard H.264 MP4 files usually work best; unusual codecs may fail to load.
Often, but not always. If the source MP4 is already optimized, a new WebM at high quality can be similar in size or larger.
Last updated: May 14, 2026
