Free MKV to MP4 converter for macOS

Convert MKV to MP4 on your Mac — no app to install

QuickTime won't open MKV files, and macOS never will natively. Instead of installing HandBrake or fighting VLC's export profiles, drop the file here — it is repackaged into an MP4 right in Safari or Chrome, usually in seconds and with zero quality loss.

Up to 20 files of 1.5 GB each per batch. No .dmg, no Gatekeeper prompt, no upload — your videos never leave your Mac.

No install
Works in Safari
Opens in QuickTime
No quality loss
No upload

Drop MKV files here

or browse your device — up to 20 files, 1.5 GB each

Conversion starts automatically and never uploads your video anywhere.

Files are processed on your device with FFmpeg compiled to WebAssembly — nothing is uploaded, logged, or stored.

How to convert MKV to MP4 on a Mac

Three steps in the browser your Mac already has — no downloads, no uploads.

Open this page in Safari, Chrome, or Firefox
No download, no .dmg, no Gatekeeper warning — the converter is FFmpeg compiled to WebAssembly and runs inside the browser your Mac already has. The first visit fetches a one-time ~31 MB engine that gets cached for later.
Drag your MKV files in from Finder
Drop up to 20 Matroska (.mkv) files, up to 1.5 GB each, straight from a Finder window into the zone above. The tool inspects each file and picks the fastest path: H.264, H.265/HEVC, and AV1 video is copied into the MP4 container bit-for-bit, so most files finish in seconds with zero quality loss.
Download and open in QuickTime
Preview any finished file right on the page, then save it to your Downloads folder — one by one or all at once. The resulting MP4 opens in QuickTime Player, imports into iMovie, and AirPlays to an Apple TV. Everything was processed locally; nothing was uploaded.

This tool vs HandBrake vs VLC on Mac

The usual Mac advice for MKV files is "install HandBrake" or "use VLC". Both work — but both are transcoders first, and repackaging a container is a much smaller job than re-encoding video.

	This tool	HandBrake	VLC
Install required	None — runs in the browser	Yes — app download	Yes — app download
Lossless by default	Yes — remux for H.264/HEVC/AV1	No — always re-encodes	No — re-encodes unless you build a custom profile
Typical time (2 GB file)	Seconds	10–40 minutes	Minutes (re-encode) or seconds (manual stream copy)
Text subtitles kept	Yes — converted to MP4 timed text	Burn-in or soft subs, configured per rip	Often lost in Convert mode
Privacy	Local — nothing uploaded	Local	Local

HandBrake and VLC are excellent free apps — if you need to shrink a file or change codecs, use them. If you just need an MKV to open in QuickTime or iMovie, a remux is faster and lossless.

MKV to MP4 on Mac — questions

Why won't QuickTime Player open my MKV file?

Apple has never added Matroska support to macOS — QuickTime Player, Finder previews, and Photos all reject .mkv files no matter which codecs are inside. The video data itself is usually fine; it is only the container QuickTime refuses. Repackaging the same streams into an MP4 makes the file open natively, with no quality change.

Do I need to install anything on my Mac?

No. Unlike HandBrake, VLC, or paid Mac converter apps, this tool has nothing to download from the App Store or the web — no .dmg, no admin password, no Gatekeeper 'unidentified developer' prompt. It runs entirely inside Safari, Chrome, or Firefox, and keeps working offline once the page has loaded.

Does it work in Safari on macOS?

Yes. Safari, Chrome, Firefox, and Edge on macOS all run the WebAssembly conversion engine. Any Mac from roughly the last decade — Intel or Apple Silicon — running a current browser will work.

Is it fast on Apple Silicon (M1–M4)?

Very. For H.264, H.265/HEVC, and AV1 sources the tool performs a remux — a stream copy with no re-encoding — so the work is mostly moving bytes, and even multi-gigabyte files finish in seconds. On the rare VP8/VP9 file that must be re-encoded, an Apple Silicon Mac is still several times faster than an older Intel MacBook.

Will the converted MP4 work in iMovie and Final Cut Pro?

Yes, in the common case. Nearly every MKV carries H.264 or H.265/HEVC video, and an MP4 with those codecs imports directly into iMovie, Final Cut Pro, QuickTime, and Photos. Only AV1 sources are an exception — the MP4 will play in Safari and Chrome, but Apple's editing apps do not read AV1 yet.

Can't VLC convert MKV to MP4 on a Mac?

It can, but VLC's Convert/Stream feature re-encodes the video by default, which takes minutes instead of seconds and costs one generation of quality; keeping the original streams requires editing a custom profile, and subtitle tracks are often lost along the way. This tool does the lossless stream copy by default and converts text subtitles to MP4's native format automatically.

Does converting reduce the video quality?

No — for H.264, H.265/HEVC, and AV1 video the streams are copied into the MP4 container untouched, so the output is bit-identical to what was inside the MKV. Re-encoding only happens for codecs MP4 players cannot handle, such as VP8/VP9 video, and the tool labels which path it took for every file.

Are my videos uploaded anywhere?

No. The entire conversion runs on your Mac, inside the browser tab — there is no upload endpoint, no queue, and no server-side copy of your video. Disconnect from Wi-Fi after the page loads and conversions keep working.

Why Macs and MKV don't get along

MKV (Matroska) and MP4 are containers — wrappers around compressed video and audio streams. macOS ships first-class support for MP4 across QuickTime, Photos, iMovie, and AirPlay, but has never supported Matroska, so a file that plays fine on a PC or in VLC simply won't open anywhere in Apple's ecosystem.

Because the streams inside are usually H.264 or H.265/HEVC — codecs macOS understands perfectly — the fix is not converting the video at all, just moving it between containers. That is what this page does, using FFmpeg compiled to WebAssembly inside your browser: a lossless remux for compatible codecs, and an automatic re-encode only for the rare MKV carrying VP8/VP9 video or DTS audio.

This is the same engine as the main MKV to MP4 converter — same 20-file batches, same 1.5 GB per-file limit, same privacy model: everything runs on your Mac, and nothing is ever uploaded.

Your videos never leave your Mac

Every conversion runs locally through WebAssembly FFmpeg. We never receive, store, or even see a byte of your video — there is no upload endpoint to send it to. Close the tab and nothing about your files persists anywhere.