Is my video uploaded anywhere?

No. Conversion runs entirely inside your browser using FFmpeg.wasm — a WebAssembly port of FFmpeg. Your files never leave your device. No server receives them.

Completely free — no sign-up, no credit card, no watermarks on output.

What codec does the MP4 output use?

H.264 (libx264) for video and AAC for audio, at CRF 23 with medium preset. This is the standard "good quality, reasonable size" setting used by most video editing software. The output is compatible with every device and platform.

Will the video quality change?

There is a small quality reduction from re-encoding, which is unavoidable with any format conversion. CRF 23 is a visually lossless setting for most content — you won't notice a difference in normal playback.

Can I preserve the original quality exactly?

Only if the source is already H.264/AAC inside a different container (like MOV or MKV). In that case the re-encode is minimal. For other codecs (AVI DivX, WebM VP9), a quality reduction is inherent to re-encoding.

No upload · 100% free · Works in your browser

Convert video to MP4, free.

Turn MOV, AVI, MKV, WebM or any video into a universally playable MP4 — right in your browser.

Why MP4 is the universal video format

The MP4 container with H.264 video and AAC audio has become the global standard for a simple reason: everything plays it. iPhones record in MOV by default. Android devices use MP4. GoPros output MP4. But when you share across platforms, MOV from a Mac might not play on Windows, and MKV from a download won't play on a smart TV without transcoding.

Converting to MP4 solves all of this. WhatsApp, iMessage, Slack, Discord, Google Drive, Instagram, TikTok, YouTube — every one of them accepts MP4 without complaint. It's the one format you can share with anyone and know it will just work.

How to convert video to MP4 online

1
Drop your video
Drag MOV, AVI, MKV, WebM, or any other video format onto the converter, or click to browse.
2
FFmpeg loads in your browser
The first use downloads FFmpeg.wasm — about 30 MB, one time per browser session. No data about your video is transmitted.
3
Conversion runs locally
FFmpeg re-encodes the video to H.264/AAC MP4 entirely inside your browser tab. Progress is shown in real time.
4
Download the MP4
Save each converted file individually, or download everything as a ZIP.

MOV vs MP4 — what's the difference?

MOV is Apple's container format, developed for QuickTime. It uses the same H.264 or HEVC video codec as MP4, just in a different wrapper. On a Mac or iPhone, MOV plays natively. On Windows without QuickTime or a codec pack, it often doesn't — or plays without audio.

MP4 is the ISO standard container format built on the same MPEG-4 foundation. It is natively supported by Windows, Android, every major browser, and virtually every media player on earth. Converting MOV to MP4 is often just changing the container — the video data itself may not need re-encoding, making it fast with no quality loss.

Frequently asked questions

Compatibility

MP4 with H.264 video and AAC audio is the most universally supported video format. Every phone, tablet, computer, TV, messaging app, and social platform accepts it without plugins or extra software. If you need one format that just works everywhere, MP4 is it.

MOV (iPhone, Mac), AVI (Windows), MKV (downloaded content), WebM (web/YouTube), FLV (Flash), WMV (Windows Media), M4V (iTunes), 3GP (older phones), and more. If FFmpeg can read it, this converter can process it.

Privacy & Safety

Output Quality