How it works
CompressLab uses your browser’s built-in video encoder (WebCodecs) — the same hardware encoder your graphics card uses for video calls. That is why it is fast and why your videos stay on your device: there is no server that could see them.
- Add videos. Drop files or a whole folder (subfolders are kept). Anything that isn’t a video is skipped.
- Choose what it is for. Discord, email, WhatsApp, “free up space”, TikTok, TV — or set your own size with the slider. The slider sets the size of the longest video; every video is compressed at the same rate, so none ends up bigger.
- Pick a folder and start. Compressed videos are saved there, in the same folder structure. You can keep adding videos while others are being compressed.
What makes it different
- No upload, no limits. Online compressors usually cap files at 500 MB–1 GB and make you wait for the upload. Here a 4 GB file is fine.
- Exact size. Need it under 10 MB? You get under 10 MB — with the best resolution that still looks good at that size.
- Preview first. Press ▶ next to a video to see 5 seconds before and after, and the expected final size.
- Keeps the capture date and location, so your gallery doesn’t think the video was shot today (or remove them with one click before sharing).
- Pro tools when you need them: 40+ presets, TV commercial specs for 31 countries, loudness normalization (EBU R128, −14 LUFS for YouTube), App Store previews, splitting into parts, reading a delivery spec from a PDF or screenshot.
Which settings should I use?
For most people the answer is: none. Pick what the video is for and CompressLab chooses the codec, resolution, frame rate and sound for you. If you want control, the size slider is the one setting that matters — everything else follows from it.
| You want to… | Choose | What you get |
|---|---|---|
| Post in a Discord chat | Discord | Under 10 MB, plays inline |
| Attach to Gmail, Outlook or Yahoo | 18 MB file — fits a 25 MB message | |
| Send on WhatsApp, iMessage or Telegram | WhatsApp · Telegram | 720p H.264, sends fast, app doesn’t crush it |
| Free up space on your drive or phone | Free up space | Same resolution, visually identical, often 3–10× smaller |
| Upload to TikTok, Reels or Shorts | TikTok · Reels · Shorts | 1080×1920, 30 fps, platform-friendly bitrate |
| Play from a USB stick on a TV | TV (or the TV & USB section) | Formats your TV actually plays, sized to fit the stick |
How much can a video be compressed?
Phones and cameras record at very high bitrates because they have to encode in real time with little processing power. A 1-minute 4K iPhone clip is about 350–400 MB; the same minute at 1080p with a careful encoder looks almost the same at 40–60 MB. Screen recordings shrink even more because most of the screen doesn’t move. In practice:
- Phone video (4K/1080p): 5–10× smaller with no visible difference on a phone or laptop screen.
- Screen recordings: 10–20× smaller, text stays sharp.
- Already-compressed downloads or exports: 1.2–2× — there is little left to remove without lowering resolution.
If a target is too small for the video’s length, CompressLab tells you the smallest size that is technically possible — with and without sound — instead of producing something unwatchable.
Why compress in the browser instead of an online service?
Typical online compressors upload your file to their server, compress it there and make you download the result. That means waiting for two transfers, a file size cap (often 1 GB, or 100–500 MB on free plans), sometimes a watermark — and your private video sitting on someone else’s server. CompressLab does the work on your own computer, so the only limits are your disk space and patience. On a laptop from the last five years a 10-minute 1080p video usually takes one to three minutes.
Is it as good as HandBrake?
HandBrake is excellent desktop software with more knobs. CompressLab covers the jobs people actually use HandBrake for — getting a file under a size, converting iPhone HEVC to H.264, batch-compressing a folder — without installing anything and with presets that already know each platform’s limits. If you need two-pass x265 at “veryslow”, use HandBrake; if you need a video under 10 MB in the next minute, use this.
Questions
Is it really free?
Yes. There is no watermark, no sign-up and no file size limit. The site is supported by ads.
Are my videos uploaded anywhere?
No. Compression runs entirely in your browser using your computer’s video encoder. You can even disconnect from the internet after the page has loaded.
Which browsers work?
It works best in Chrome, Edge or Opera on a computer. Choosing a save folder also needs one of these; in other browsers the files are downloaded instead.
Why is my compressed video bigger than the original?
If the original is already very compressed and you choose a high quality preset, re-encoding can’t make it smaller. Use the size slider or the “Free up space” mode, which never goes above the source bitrate.
Is there a file size or length limit?
No. Files are processed on your computer, so multi-gigabyte videos and hour-long recordings work. Very long videos simply take longer.
Does it work on iPhone or Android?
Video encoding in the browser works best on a computer. Recent Chrome on Android works for short videos; Safari on iPhone does not yet support everything needed.
Will compressing remove the audio?
No — sound is kept by default. Only for extremely small targets will CompressLab suggest dropping it, and it always asks first.
Last updated: 2026-10-30