Free video compressorShrink videos right in your browser.

Drop videos here

or click to choose · mp4 / mov / m4v / webm · multiple files OK

About Byte Massacre, the free video compressor

Byte Massacre is a free online video compressor that runs entirely in your browser. There is nothing to install and no account to create. Your video is never uploaded to a server — it is compressed on your own computer, so unreleased work and client footage stay private. It reads MP4, MOV, M4V and WebM, exports lightweight MP4 files ready for websites, CMSs and social media, and can also turn part of a video into an animated GIF.

How to compress a video

  1. Drag and drop your video onto the box at the top of the page (or click to choose). You can add several videos at once.
  2. Pick a quality: High, Standard or Light. If unsure, Standard is a good choice.
  3. Press “Compress”. When it finishes, compare it with the original and download the result.

Features

No upload, fully private

All processing happens inside your browser. Your video is never sent to an external server.

Smaller files, same look

Instead of forcing a target file size, it uses quality-based encoding (x264 CRF): each scene gets just as much data as it needs to look right, so dark or fast-moving scenes stay clean. In one example, a 2-minute Full HD video went from 157.8MB to 12.7MB (about 1/12) with no visible difference in normal playback.

MP4 that plays everywhere

Exports H.264 / AAC MP4 that plays on iPhone, Android and every major browser, optimized so web playback starts before the whole file loads.

Clean-looking GIFs

Builds a custom 256-color palette for each video before converting, so GIFs keep their colors. You can also make them choppy, stop-motion style, to save even more space.

Free, no sign-up, no limits

Compress as many videos as you like. No email address or login required.

FAQ

Is it really free?
Yes. It is free, requires no sign-up, and has no usage limits.
Are my videos uploaded anywhere?
No. Compression happens entirely inside your browser, and your video is never sent to an external server.
Which file formats are supported?
It reads MP4, MOV, M4V and WebM, and exports MP4 (H.264) or GIF. It also works for converting MOV files from an iPhone or camera into lightweight MP4.
How much smaller will my video get?
It depends on the footage, but Full HD video from a camera or phone often shrinks to between a fraction and a tenth of its original size. Choosing Light or a smaller width makes it even smaller.
How much quality is lost?
Standard aims for quality that is hard to tell apart from the original in normal playback. After compressing, you can compare the two side by side.
How long does it take?
It depends on your computer, but a 2-minute Full HD video usually takes from a few minutes to around 15 minutes. Keep the tab open while it works.
Does it work on phones?
It runs, but because of memory and speed limits, Chrome or Edge on a computer is recommended.
Can it compress large videos?
Browsers limit how much memory a page can use, so videos up to about 1.5GB are recommended. Larger files may stop midway.
Should I use GIF or MP4?
For websites, a muted looping MP4 is smaller and looks better. GIF is best for social media, email and chat, where video is not available.