Free

Free Video Converter Online

A free video converter online: turn MOV, MKV, and WebM into MP4 that plays everywhere.

Free tool · No sign-up · Private

Drop in a video

MOV, MKV, WebM, AVI — up to ~100MB. Converts to MP4 (H.264 + AAC) that plays everywhere. First run loads the video engine (~30 MB) — once, then it's instant. Your file never leaves this browser.

Private by design. Conversion runs 100% in your browser with ffmpeg.wasm. Your video is never uploaded, stored, or seen by anyone.

Formats & limits

What you can convert

Straightforward limits, stated plainly.

MOV, MKV, WebM, AVI in

Any common container up to ~100MB. Already-MP4 files are rejected politely — there's nothing to convert.

MP4 (H.264 + AAC) out

The most compatible combination in existence, with faststart so it streams before fully downloading.

Remux first, re-encode fallback

Compatible codecs are repackaged instantly with zero quality loss; incompatible ones are re-encoded. You're told which happened.

Private by design

First run loads the ~30 MB video engine once. No accounts, no uploads, no watermarks.

How it works

Three steps to MP4

Drop in a video

Choose a MOV, MKV, WebM, or AVI file up to ~100MB. It stays on your device — nothing is uploaded.

Convert

Press “Convert to MP4”. The tool tries an instant remux first, and re-encodes only if the codecs demand it.

Preview and download

Watch the converted MP4 right on the page, see how it was converted, then download it.

Use cases

When converting helps

One format to play them all.

iPhone videos on Windows

MOV files from iPhones confuse some Windows players and older TVs. MP4 just plays.

MKV for sharing

MKV is a great archive format but a poor sharing one. Convert to MP4 before sending to anyone.

WebM for editors

Many desktop editors and phones handle WebM poorly. An MP4 intermediate edits smoothly everywhere.

Uploads that demand MP4

Plenty of sites, forms, and course platforms only accept MP4. Convert once, upload anywhere.

FAQ

Converter questions

Which formats can I convert to MP4?

MOV (iPhone/Mac), MKV, WebM, and AVI — anything your browser's file picker hands over. The output is always MP4 with H.264 video and AAC audio, the combination that plays on virtually every device.

How fast is the conversion?

Often seconds. The tool first tries a remux — repackaging the existing video and audio streams into MP4 without touching them, which is instant and loses zero quality. Only if the codecs can't live in MP4 (like VP9 or AV1) does it fall back to a full re-encode, which takes longer. The result screen tells you which path was used.

Will I lose quality?

Not with a remux — streams are copied bit-for-bit. With a re-encode there's a small, usually invisible quality cost. Either way the tool reports exactly what it did, so there are no surprises.

Do subtitles survive the conversion?

No — only the video and audio streams are carried over; subtitle tracks are dropped. If you need burned-in subtitles, add them in a video editor first.

My iPhone video won't play on Windows. Will this fix it?

Usually, yes. iPhone videos are MOV files that some Windows players and older devices choke on. Converting to MP4 (H.264 + AAC) fixes playback in the vast majority of cases.

Is my video uploaded anywhere?

No. The conversion runs locally with ffmpeg.wasm in your browser tab — your file never touches a server, which is also why there are no queues or watermarks.

Keep exploring