Max file size: 250MB

Download your converted MP4 to MKV file here when ready.

Hold tight, processing may take a minute...

How to convert MP4 to MKV (quick steps)

Step 1: Add a video: drag & drop an MP4 or paste a URL.

Step 2: Click Convert to MKV: the tool will remux when compatible (fast, no quality loss) or transcode if needed for compatibility.

Step 3: Preview & download: check playback, then save the .mkv file to your device.

Works on Windows, macOS, Linux, and mobile browsers.

Why MKV? (and when to stick with MP4)

Matroska (MKV) = flexible container: supports multiple audio tracks, soft subtitles, chapters, and a variety of codecs.

MP4 = widest device support: best for built-in players and some social networks.

If you need extra tracks or subs, MKV often fits better. For maximum compatibility, MP4 may still be preferable.

Safe, private & online

Files are processed securely and deleted after conversion. Free demo supports smaller files but you can sign up to increase limits and unlock batch processing.

The open-source code for this project is available on GitHub, offering a starting point for those interested in building their own media conversion tools or video editing application.

Do more with Shotstack

If you need to run MP4 to MKV at scale—batch jobs, user uploads, CI/CD steps — Shotstack's Video Editing API turns this demo into a repeatable pipeline with templates, queues, retries, webhooks, and global delivery via the Serve API.

Frequently asked questions (FAQs)

When codecs/parameters are MKV-compatible, the tool remuxes (rewraps) instead of re-encoding, so quality is preserved. If not compatible, it transcodes (slower; may change size/quality).

Yes. The UI supports Upload or URL input.

The demo caps the source video at 250 MB.

MKV isn't usually supported for inline browser playback; download the file and play it in a desktop/mobile player.

Where compatible, MKV supports soft subtitles and multiple audio tracks; those tracks are preserved on remux, and included on transcode where supported.

Yes. The demo is built on Shotstack's Ingest API; production use-cases typically pair it with templated jobs, queues, webhooks, and CDN delivery.

Get started with Shotstack's video editing API in two steps:

  1. Sign up for free to get your API key.
  2. Send an API request to create your video:
    curl --request POST 'https://api.shotstack.io/v1/render' \
    --header 'x-api-key: YOUR_API_KEY' \
    --data-raw '{
    "timeline": {
    "tracks": [
    {
    "clips": [
    {
    "asset": {
    "type": "video",
    "src": "https://shotstack-assets.s3.amazonaws.com/footage/beach-overhead.mp4"
    },
    "start": 0,
    "length": "auto"
    }
    ]
    }
    ]
    },
    "output": {
    "format": "mp4",
    "size": {
    "width": 1280,
    "height": 720
    }
    }
    }'

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