Frequently asked questions
Are my videos uploaded anywhere?
No. The whole compression happens inside your browser on your device, and the video is never sent to a server. That privacy is the main upside of doing it this way.
Is there a size or length limit?
Yes, the limit is 1 GB per video and one video at a time, and files near that size are the most likely to run out of memory. Everything runs on your device, so large or long videos use a lot of memory; on phones or low-memory machines the tab can slow down or even crash. If that happens, try a lower resolution or a shorter clip.
What are the two engines?
Fast mode uses your device's own hardware video encoder (best in Chrome and Edge) and needs no download. Compatible mode uses a built-in engine that works more widely but downloads about 31 MB the first time and is much slower. It picks automatically, and you can override the choice.
Will the quality drop?
Compressing re-encodes the video, so some quality is lost, more so at lower resolutions and the Smaller setting. Resolution is the biggest lever. If the result would end up larger than your original (common for videos that are already compressed), we keep your original instead.
Which formats can I use?
It reads most common video files and outputs either MP4 (H.264), which plays almost everywhere, or WebM (VP9), which can be smaller. If your browser cannot make the format you picked, the tool switches to the one it can.
Why is it slow, and can it crash?
Video compression is heavy on your processor and memory. The compatible engine especially can take several minutes for a few minutes of footage, and very large files may make the browser run out of memory and crash the tab. Keep the tab open and awake while it works, and use a lower resolution for big files.