What is video compression?
Video compression reduces file size by removing visual data that is hard or impossible to notice. A raw 1-minute 1080p recording can be several gigabytes. After compression with H.264 or VP9 at a sensible quality setting, the same clip is typically 50-200 MB with no visible difference on most screens.
Everything runs directly in your browser. Your files are never uploaded. The whole process happens in memory on your device.
How quality works
The quality slider maps to a CRF (Constant Rate Factor) value internally. Lower CRF means better quality and a larger file. Around 50% is a good starting point for most videos. Push it higher if you need a smaller file, or lower if you are archiving something and want to keep it near-original.
Resolution downscaling
Halving the resolution cuts file size by roughly 75% before compression even starts, because there are four times fewer pixels to encode. Dropping a 1080p video to 720p is the single most effective way to shrink a file. If you pick a resolution higher than your source, the original dimensions are kept.
MP4 vs WebM
MP4 (H.264) is the most compatible format. It plays in every browser, every phone, every smart TV, and every editing app. Use it unless you have a specific reason not to.
WebM (VP9) is an open format from Google. It produces slightly smaller files at the same visual quality, but takes a bit longer to compress. Good for web delivery where you want open standards and slightly better efficiency.
How compression works in the browser
When you use GPU mode, the tool uses your browser's WebCodecs API to encode video in real-time using your hardware. It is fast and works well for most files. If your browser or device does not support it, the tool automatically switches to a software encoder that runs via WebAssembly. On first use that downloads about 30 MB to your browser cache, then loads instantly on future visits. Either way, nothing leaves your device.
How to compress a video
- Drop one or more video files onto the drop zone, or click Browse files.
- Choose your quality, resolution, codec, and whether to keep audio.
- Click Compress. Files are processed one at a time and each row shows progress while it runs.
- Download each file from its row, or use Download all as ZIP when multiple files are ready.
Common uses
Email and messaging
Most email clients cap attachments at 25 MB and apps like WhatsApp have their own limits. Drop the resolution to 480p and lower the quality to shrink a phone recording enough to share directly.
Web embedding
Nobody wants to download 500 MB to watch a two-minute explainer. Compress to 720p at around 50% quality for fast-loading embeds that still look good.
Archiving
Raw screen recordings and phone videos add up fast. Run them through at high quality and original resolution to cut the file size significantly with no visible difference.
Stripping audio
Tutorial recordings and product demos often have background noise or unwanted audio. Check "Remove audio" to strip the audio track before adding new voiceover in an editor.
Frequently asked questions
Why does it download 30 MB on first use?
The software encoder that runs in your browser is about 30 MB. It downloads once and is cached, so future visits load instantly. It only downloads if you use CPU mode or if GPU mode is not supported on your device.
How long does compression take?
It depends on your device, the video length, and the settings. GPU mode is real-time so a 5-minute video takes roughly 5 minutes. CPU mode is slower and can take several times the video length on a typical laptop.
My video format is not listed. Will it still work?
Most common formats work fine. Just drop the file and it will be read correctly. The output will be in your chosen codec (MP4 or WebM) regardless of the input format.
Can I compress videos larger than 4 GB?
Browser memory limits apply. A 4 GB source file needs roughly 8-10 GB of free RAM to process. For very large files, splitting them first or compressing in shorter segments will help.
Is there a limit to how many files I can add?
No limit. Files are processed one at a time so memory from the previous file is freed before the next one starts.