Is the MP4 to MKV converter free?

Yes — Morphix's MP4 to MKV converter is 100% free with no sign-up, watermarks, or file-size limits beyond your device's memory.

Are my MP4 files uploaded to a server?

No. Conversion runs entirely in your browser using WebAssembly — your MP4 files never leave your device.

Does it work offline?

Yes. After the first visit, the MP4 to MKV converter works fully offline.

Back to Morphix File Converter

MP4 → MKV

MP4 to MKV Converter

Rewrap MP4 videos into flexible MKV containers.

Drop files here

or browse from your device

images · audio · video · documents · archives · up to ~500MB

100% Private

Runs in your browser. No upload.

Instant

No queue, no server roundtrip.

Offline-ready

Works after first load.

Why convert MP4 to MKV?

MKV can hold multiple audio tracks, subtitles and chapters in one file. Media servers like Plex and Jellyfin treat it as a first-class format, which is why home libraries standardise on it.

How it works

Drop your MP4 file above and Morphix decodes it locally, then re-encodes it as MKV using WebAssembly + the browser's native codecs. Nothing is ever uploaded — your files stay on your device. Batch as many files as your machine can handle.

Related converters

MKV to WEBM AVI to WEBM MOV to WEBM MPG to MP4 VOB to MP4

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