FAQ
Video Compressor Frequently Asked Questions
Everything you might want to know about our free online video compressor and how to reduce video file size online.
Is MP4 Compress free to use?
Yes. MP4 Compress is 100% free, with no signup required, no watermarks added to your videos, and no daily upload cap.
How does MP4 Compress reduce video file size?
Our video compressor re-encodes your MP4 with a smarter bitrate target, removing redundant data your eyes won't notice. The result is a smaller file that looks visually identical to the original.
Are my videos uploaded to a server?
No. All compression happens locally in your browser using WebAssembly. Your videos never leave your device, which keeps them private and makes the process much faster than other online tools.
What video formats are supported?
We support MP4, MOV, WebM, AVI, MKV, and most other common video formats. The output is always a clean, web-friendly MP4.
Is there a maximum file size?
There's no hard cap from us, but performance depends on your device's RAM. Most modern computers handle multi-gigabyte 4K files comfortably.
Will my video lose quality after compression?
With our balanced and high-quality presets, the difference is virtually invisible to the human eye. Maximum compression trades some sharpness for the smallest possible file.
Does MP4 Compress work on mobile?
Yes. The interface is fully responsive and the compression engine works in mobile browsers — though large 4K files compress faster on a desktop.
Can I compress multiple videos at once?
Right now you compress one video at a time. Batch compression is on our roadmap.
Why is my compressed file not much smaller?
Already-optimized videos (such as files downloaded from streaming services) are hard to compress further without quality loss. Try the maximum compression preset, or downscale the resolution.
Do you keep any logs of what I compress?
No. We don't even know what file you compressed — the compression happens entirely on your machine.