Frequently Asked Questions

No. Your video is processed entirely inside your browser using WebAssembly. It never leaves your device and is never sent to any server. We do not collect, store, or see any of your files.

No. There are no accounts, no tracking of uploaded files, and no persistent storage of any kind on our end. The page does not even require cookies to function.

Yes. Because everything happens locally in your browser, it is safe to use on confidential videos — corporate recordings, personal content, anything. The data never travels over the network.

It depends on the quality slider. The default (balanced) targets roughly 50% of the original bitrate — for most content that's hard to notice. Move the slider left to keep more quality, right to shrink the file further. The tool always targets a bitrate below the original, so the output is always smaller.

It controls what fraction of the original bitrate the encoder targets. At "high quality" (~85% of input bitrate) the result is nearly identical to the source but only modestly smaller. At "maximum compression" (~20% of input bitrate) the file gets very small but visible quality loss is likely, especially on high-motion content.

"Best compression" uses H.264 (libx264), the same codec as most MP4 files. It's slower but reliably shrinks any source. "Fast compress" uses MPEG-4, which encodes faster but is less efficient than H.264 — best for non-H.264 sources like old AVI or MOV files.

Only if you specifically need a smaller resolution. Dropping from 1080p to 720p cuts video data by about 56%. If your goal is just a smaller file at the same resolution, the quality slider is usually enough.

There is no hard cap, but your browser must hold the entire file in RAM. Devices with 8GB+ of RAM generally handle files up to 2–4GB without issues. The tool shows a warning for files over 1GB. Very large files may cause the tab to run out of memory.

The first time you use the tool, your browser downloads approximately 30MB of the FFmpeg WebAssembly binary. This is cached by the browser, so all subsequent compressions start immediately.

Video encoding is computationally intensive. WebAssembly is fast, but it is still running on your CPU via JavaScript. Longer videos, higher resolutions, and slower presets all increase encoding time. For a typical 10-minute 1080p video, expect 2–10 minutes depending on your device.

FFmpeg supports virtually every video format in existence. You can upload MP4, MKV, MOV, WebM, AVI, WMV, FLV, and more. If your browser can read the file, FFmpeg can usually process it.

You can compress to MP4 (H.264/AAC), MKV (H.264/AAC), WebM (VP9/Opus), or MOV (H.264/AAC). MP4 is the most universally compatible format and is recommended for sharing.

Yes. By choosing a different output format from your input, you are effectively converting. For example, you can upload an MKV and download an MP4.