Video Compressor — Compress MP4 Online Free, No Upload
Compress MP4, MOV, and WebM videos right in your browser — no upload, no watermark, no sign-up. Three quality presets powered by FFmpeg on your device.
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Balanced is right for sharing on WhatsApp, email, or the web.
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Compress video in your browser — private by construction
Most "compress video online" sites work the same way: you upload your video to their server, they compress it, you download the result — and your recording sits on someone else's machine the whole time. This tool inverts that. It runs FFmpeg, a widely used open-source video engine, compiled to WebAssembly inside your browser. The engine comes to you; your video goes nowhere.
Why videos from your phone are so large
Phone cameras record at generous bitrates because at capture time the camera can't know what detail will matter. At 60 Mbps, one minute of 4K is about 450 MB. Re-encoding with H.264 at a higher compression setting keeps the quality your eyes actually perceive while discarding the headroom, which is where the size reduction comes from. How much you save depends on the source, so the result card shows the new size and the percentage saved.
Three presets, no jargon required
Light re-encodes at CRF 23 with the original resolution and 128 kbps audio — the least quality loss, the smallest saving. Balanced uses CRF 28, caps the width at 1280 pixels and uses 96 kbps audio — the sweet spot for WhatsApp, email and web embeds. Strong uses CRF 32 and caps the width at 854 pixels (480p) for the smallest files. All three produce standard MP4 (H.264 + AAC) with faststart enabled, and none of them upscales a video that is already small.
Getting a video under an email or upload limit
Gmail allows attachments up to 25 MB, and email encoding adds roughly a third to an attachment's size, so leave some margin. That is about 200 megabits to spend, so the average bitrate you can afford falls as the clip gets longer: under 6.7 Mbps for 30 seconds, under 3.3 Mbps for a minute, under 1.7 Mbps for two minutes and under 0.7 Mbps for five. Cut the clip to just the part you need with the video trimmer first, then compress it with Strong; trimming helps a lot because every second you remove is bitrate you no longer have to pay for.
When this is the wrong tool
Compression here means re-encoding, so it always costs some quality, and running it twice on the same file compounds that. If you only need a different container or format, use the video converter; if you only want to cut, the trimmer's Fast mode copies the video without re-encoding at all. Very long or very high-resolution files can exceed a phone's memory, in which case a desktop browser or shorter pieces are the fix.
No watermarks, no queues, no accounts
Because compression happens on your hardware, there is nothing to meter: no daily quotas, no watermark in the corner, no email wall before download. Pair it with the video trimmer to cut before compressing, or the video converter when you need a different format entirely.
Frequently asked questions
- Is my video uploaded to a server?
- No. This compressor runs FFmpeg compiled to WebAssembly inside your browser tab. The engine downloads once (~31 MB); your video is read, re-encoded, and saved entirely on your own device. You can watch the network tab — no video bytes ever leave your machine.
- How can I get a video under Gmail's 25 MB attachment limit?
- Work out the total bitrate you can afford: 25 MB is 200 megabits, so a 30-second clip must average under 6.7 Mbps, a 1-minute clip under 3.3 Mbps, and a 2-minute clip under 1.7 Mbps (audio included). Email encoding adds roughly a third to an attachment's size, so leave some margin. Phone footage is usually far above that, so pick Strong for anything over a minute or two, trim off the parts you don't need first, and check the size on the result card before attaching. If it is still too big, split it into shorter clips.
- How much smaller will my video get?
- It depends entirely on the source, so the tool shows the original size when you choose the file and the new size and percentage saved when it finishes, instead of promising a percentage. Phone and screen recordings shrink the most because cameras record at very high bitrates (4K at 60 Mbps is about 450 MB per minute). A video that was already compressed for the web, such as a download from a video site, has little left to remove and may barely change.
- Which preset should I choose?
- Balanced (the default) re-encodes at CRF 28, caps the width at 1280 pixels and uses 96 kbps audio — right for WhatsApp, email and web embeds. Light uses CRF 23, keeps the original resolution and 128 kbps audio: the least quality loss, the smallest saving. Strong uses CRF 32 and caps the width at 854 pixels (480p) for the smallest file, which suits previews and chat. None of them ever upscales a small video.
- Can I compress just part of a video?
- Yes, and it is the fastest way to a small file: cut the part you need first with the video trimmer, then use the "Compress this clip" button next to its download link. The clip is handed over directly, so you do not re-select the file, and everything still runs on your device.
- What format does the compressed video come out in?
- Always MP4 with H.264 video and AAC audio, with the index moved to the front of the file so it starts playing before it has fully loaded. That combination plays on phones, browsers, TVs and editors. If you need WebM, MOV or AVI instead, use the video converter.
- Is there a file size limit?
- The tool sets no limit of its own, but files over about 2 GB are more than the in-browser engine can read reliably, and everything runs in your browser's memory, so the practical ceiling is your device. Large files work best on a desktop browser with other tabs closed; phones run out of memory sooner. A file over about 2 GB is more than the in-browser engine can read reliably: the tool warns you as soon as you choose one, and the fix is to cut it into smaller pieces first. If a long video stops partway, trim it into shorter pieces and compress each.
- Why is it slower than online compressor sites?
- Cloud services use server farms; this tool uses your own processor, which is the price of never sending the video anywhere. Longer, higher-resolution videos take longer and the progress bar shows how far along it is. The engine also loads once per session, so the first run includes a short download.
From the blog
- Lossless Video Trimming: Fast Cut vs Precise Cut
Lossless video trimming copies your footage without re-encoding, but cuts snap to keyframes. See when to pick Fast or Precise mode, with real numbers.
- Does an Online Tool Upload Your File? A 2-Minute Test
Does an online tool upload your file? Use the browser's Network tab and an offline test to check any video, PDF or image tool in two minutes.
- Compress a Video Without Uploading It (2026 Guide)
Compress video without uploading it: shrink a video by 50–80% for WhatsApp, email or the web, right in your browser. Step-by-step guide with presets.
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