Stax
Tools

Video Compressor — Compress MP4 Online Free, No Upload

Compress MP4, MOV, and WebM videos right in your browser — no upload, no watermark, no size limit. Three quality presets powered by FFmpeg on your device.

Drop a file here or click to browseMP4, MOV, WebM, AVI, MKV — one file at a time🔒 Processed on your device — never uploaded

Balanced is right for sharing on WhatsApp, email, or the web.

Compress video in your browser — private by construction

Every popular "compress video online" site works 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, the same open-source engine behind most video software on earth, 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 — 4K at 50–100 Mbps is common — because at capture time the camera can't know what detail will matter. That's why a one-minute clip can weigh 400 MB. Re-encoding with H.264 at CRF 28 keeps the visual quality your eyes actually perceive while discarding the headroom, which is where the routine 50–80% size reductions come from.

Three presets, no jargon required

Light re-encodes at CRF 23 with the original resolution — archival quality, moderate savings. Balanced caps width at 1280 pixels and uses CRF 28 — the sweet spot for WhatsApp, email attachments, and web embeds. Strong drops to 480p for the smallest files. All three produce standard MP4 (H.264 + AAC) with faststart enabled, so the result streams instantly anywhere.

No watermarks, no queues, no accounts

Because compression happens on your hardware, there is nothing to meter: no per-file limits, 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 much smaller will my video get?
Typically 50–80% smaller on the Balanced preset, depending on the source. Phone recordings compress dramatically because cameras record at very high bitrates; already-compressed downloads shrink less. The result card shows the exact size reduction after each run.
Which preset should I choose?
Balanced (the default) suits sharing on WhatsApp, email, or the web — it caps resolution at 720/1080p width and uses CRF 28. Light keeps the original resolution with nearly invisible quality loss. Strong drops to 480p for the smallest possible file, right for previews and messaging.
Is there a file size limit?
No artificial limit — but everything runs in browser memory, so the practical ceiling is your device's RAM. Files up to about 500 MB work well on most computers. For a very long video, trimming the part you need first (with the video trimmer) is the faster route.
Why is compression slower than online converter sites?
Cloud converters use server farms; this tool uses your CPU — the trade for total privacy. Expect roughly real-time speed on a modern laptop (a 2-minute clip takes about 2 minutes on the Balanced preset). The engine also loads once per session, so the first run includes a short download.

Related tools