Convert video to MKV

Free online conversion of 3GP, AVI, FLV, GIF, MOV, MP4, MPG, WEBM, WMV to MKV

Local-first

Drop files here

or click to select files. Supports MP4, AVI, MPG, MOV, FLV, 3GP, WEBM, MKV, WMV, GIF.

This online video conversion tool supports MP4, AVI, MPG, MOV, FLV, 3GP, WEBM, WMV, GIF and other video formats, allowing you to easily convert these formats to the highly compatible MKV format. Multi-format support: Provides support for MP4, AVI, MPG, MOV, FLV, 3GP, WEBM, WMV, GIF and other video formats, covering most common video file types. MKV output: Convert video files to MKV format quickly and easily, ensuring compatibility with more playback devices and platforms and improving your viewing experience.

Convert any video to MKV online

MKV (Matroska) is an open container that can hold multiple video, audio and subtitle tracks in a single file. This free tool converts MP4, AVI, MOV, WEBM, FLV, WMV, 3GP and MPG to MKV in your browser — ideal for bundling a movie with several audio languages and subtitle tracks into one tidy file.

Best for archiving and multi-track files

Because MKV is flexible and codec-agnostic, it is the go-to container for high-quality rips, anime and home-media libraries where you want to keep everything — original video, surround audio and subtitles — together. It preserves quality without forcing a re-mux into a more limited format.

Runs in your browser, files stay private

Conversion uses WebAssembly (ffmpeg.wasm) entirely on your device — nothing is uploaded. No sign-up, no watermark and no file limit, and you can adjust bitrate and resolution to balance MKV quality against file size.

Frequently asked questions

How do I convert a video to MKV?

Open the tool, drop in your MP4, AVI, MOV, WEBM, FLV, WMV, 3GP or MPG file, keep MKV as the output and click convert. The MKV is produced in your browser and downloads immediately.

Why convert to MKV?

MKV can store multiple audio and subtitle tracks in one file and is codec-flexible, which makes it the best container for archiving movies, anime and any video where you want to keep several tracks together.

Is the video to MKV converter free?

Yes, completely free with no sign-up, no watermark and no limit on the number or size of files you convert.

What is the difference between MKV and MP4?

Both are containers, but MKV is more flexible — it supports unlimited audio and subtitle tracks and more codecs — while MP4 is more widely supported on phones, TVs and browsers.

Are my videos uploaded to a server?

No. All processing runs locally in your browser through WebAssembly, so your videos never leave your device.