Video Compressor

How it actually works

It re-encodes a video in the browser by playing it back into a canvas and recording that canvas. A source video element feeds frames to a canvas at a chosen reduced size, canvas.captureStream grabs the moving picture, and a MediaRecorder writes it out as a WebM file at a bitrate you select from the menu, so both a smaller frame and a lower bitrate cut the final size.

This only works where the browser exposes MediaRecorder with WebM support, so it is a Chrome and Edge tool, and the output is WebM rather than MP4 because the browser records in a format its own encoder supports. The re-encoded result can be previewed and downloaded.

It works on your own file locally; the video is never uploaded, and the whole conversion happens in your machine, which also means the process runs roughly in real time while the clip plays through.

What that means for your results

The size reduction is genuine - pixels are physically resampled and the bitrate is a real encoding target handed to MediaRecorder - and because nothing leaves the device a private clip stays private. It reports honestly that it runs in Chrome and Edge rather than pretending to work everywhere.

Where it falls short — honestly

Re-encoding happens live through playback, so it is not instant and depends on your machine, and output is limited to WebM at the quality the browser encoder allows, so it cannot match a tuned desktop encoder and offers no MP4 or H.264 export. Low bitrates cost audio and fine detail, and very large or long clips strain memory because frames are handled in the page; there is no codec control beyond size and bitrate.

A real end-to-end workflow

Load a clip, drop the resolution and bitrate until the preview looks acceptable, let it re-encode, then download and compare the size. For still images the same goal is easier in Image Compressor, and if you need a delivery-ready MP4 a desktop encoder will do what this browser tool cannot.