The Complete
MKV Toolkit
for Every Platform

MKVToolNix is a free, open-source toolkit for working with Matroska MKV multimedia container files. It lets you create new MKV files, merge multiple source files into one container, split large files into smaller segments, extract individual audio or subtitle tracks, and edit metadata without touching any of the media data inside.

The toolkit ships with both a graphical interface (mkvtoolnix-gui) and a set of command-line tools: mkvmerge for muxing, mkvextract for pulling out tracks, mkvinfo for inspecting structure, and mkvpropedit for in-place metadata changes.

A typical use case is combining a video file, a DTS audio track, and an English subtitle file into a single MKV that a media player reads as one unified file. Another common task is stripping unwanted audio dubs from a Blu-ray rip to reduce file size.

Compared with HandBrake, MKVToolNix never re-encodes. HandBrake is a transcoder that converts your video to a new format; MKVToolNix only reorganizes what is already there. That makes it much faster and keeps quality exactly as it was in the source.

If you work with downloaded or ripped video regularly, MKVToolNix is one of the most useful tools you can have installed. It handles the container layer so that tools like VLC, Plex, and Kodi see your files exactly the way you intended.

Yes, MKVToolNix is completely free. It is published under the GNU General Public License version 2, which means you can download, use, copy, and even modify it at no cost. There are no premium tiers, no feature locks, and no ads built into the software itself.

The project has been maintained continuously since 2003 by developer Moritz Bunkus, who accepts donations but does not require them. The full source code is available on GitLab, so anyone can audit exactly what the program does.

Every feature — the GUI, all command-line tools, the Chapter Editor, and the Job Queue — is included in the single installer download. There is no “lite” version that holds back functionality to sell you an upgrade.

Other free MKV tools exist, but many carry adware installers or bundle unwanted software. MKVToolNix downloads directly from mkvtoolnix.download, which is Moritz Bunkus’s own distribution server, so the file you get is clean and unmodified.

In short: free to download, free to use, no strings attached. For anyone who regularly handles MKV files, this is one of the best no-cost utilities available on any platform.

Open mkvtoolnix-gui, go to the Merge tab, and click the “Add source files” button. Browse to your first MKV file and add it, then repeat for the second. Both files will appear in the Source Files panel with their detected tracks listed below.

By default, MKVToolNix treats each added file as a separate source and puts all their tracks into the output container sequentially. If you want the files to play end-to-end as a single stream, you need to “append” the second file to the first: right-click the second file in the source panel and choose “Append file.”

Set the output path at the bottom of the window, then click “Start muxing.” The two MKV files are combined into one output file without any re-encoding. If both files use the same video codec, resolution, and frame rate, the result plays back smoothly as a seamless single piece.

Note that appending works best when the two files share the same codec and resolution. Mismatched properties can cause chapter seam issues in some players, though the file itself will be structurally valid.

For the command-line approach, the command is: mkvmerge -o output.mkv part1.mkv + part2.mkv. The + operator tells mkvmerge to append part2 to part1 in the output stream.

In the Merge tab, add your MKV file as the primary source, then click “Add source files” again and select your subtitle file. MKVToolNix supports SRT, SSA/ASS, PGS (from Blu-ray), VobSub (IDX+SUB pairs), WebVTT, and several other formats directly without conversion.

Once the subtitle file is added, it appears in the track list below the video source. You can set the language code for the subtitle track (for example, “eng” for English or “jpn” for Japanese) and choose whether it should be the default or forced track by checking the relevant boxes in the track properties panel on the right.

Set your output path and click “Start muxing.” The result is a new MKV with both the original content and the new subtitle track embedded. The original video and audio are not touched at all — only the container structure changes.

To add subtitles to an existing MKV without re-creating it from scratch, use mkvpropedit instead. However, mkvpropedit only works for tracks already present in the file; to add a brand-new subtitle track you do need to mux with mkvmerge.

If you want the subtitle to appear automatically without the viewer having to enable it, tick “Default track” in the track properties. Most players respect this flag and enable the track on first play.

No. MKVToolNix never decodes or re-encodes any media. It works entirely at the container level, reading compressed bitstreams from your source files and writing them into the output MKV unchanged. Every byte of video, audio, and subtitle data in the output is identical to what was in the input.

This has two important consequences. First, there is zero quality loss. Re-encoding always introduces generation loss because every encode is a lossy interpretation of the previous data. MKVToolNix sidesteps that entirely. Second, muxing is fast — it only reads and writes data, so even a 50 GB Blu-ray remux can be processed in under a minute on a modern drive.

Because of this, MKVToolNix cannot convert video from one codec to another. If you need to change H.264 content to H.265, or convert an MP4 to a smaller file, you need a transcoder like HandBrake, FFmpeg, or StaxRip.

Think of MKVToolNix as a container editor. The media inside the container is off limits; only the packaging around it changes. This is exactly the right approach for tasks like adding subtitles, changing the default audio track, or combining two video files into one.

The lossless approach also means MKVToolNix is the correct tool for archival work where preserving the exact original bitstream matters.

Use the Extract tab in mkvtoolnix-gui. Add the MKV file, and the tool will list every track inside it along with track IDs and codec information. Tick the audio track you want to extract, set a destination file path, and click “Extract.” The audio is pulled out as a raw bitstream file in its native format.

For example, if the MKV contains a DTS-HD MA 5.1 track, extracting it produces a .dts file that contains the original DTS-HD data without any conversion. Similarly, a TrueHD track becomes a .thd file, an AAC track becomes an .aac file, and so on.

From the command line: mkvextract tracks input.mkv 1:audio_track.aac. Replace “1” with the actual track number shown by mkvinfo, and change the extension to match the codec.

One common reason to extract audio is for processing in a separate tool — for instance, running the audio through a loudness normalizer, then merging the processed file back into the MKV. Because extraction is lossless, you start the processing chain with a perfect copy of the original.

If you only want to check what audio codecs are present before extracting, run mkvinfo on the file first. The Info tab in the GUI shows the same information in a more readable tree format.

Yes, provided you download it from the official source. The authoritative download location is mkvtoolnix.download, which is operated by Moritz Bunkus, the sole developer of the project. Every release there is signed and checksummed, so you can verify you received an unmodified file.

MKVToolNix has been in continuous development since 2003, is used by millions of people, and is included in major Linux distribution repositories (Debian, Ubuntu, Fedora, Arch). The source code is fully public on GitLab and has been reviewed by the open-source community over many years.

The installer contains no adware, no browser toolbars, no bundled software, and no network calls during normal operation. It does not require an internet connection to run and does not phone home for telemetry.

Be cautious of third-party download sites that host their own copies of the installer. Some modify the installer to bundle unwanted software before re-distributing it. Always use the official mkvtoolnix.download URL to be safe.

Windows users can additionally verify the installer’s Authenticode signature in File Properties after downloading. Releases signed by Moritz Bunkus are genuine.

The core difference is that MKVToolNix is a container tool and HandBrake is a transcoder. MKVToolNix reorganizes tracks inside a container without touching the media data. HandBrake decodes your source media and re-encodes it into a new format, usually with compression settings you control.

Use MKVToolNix when you want to keep your content exactly as it is and only change the packaging: add a subtitle track, swap the default audio, strip a dub you never watch, or merge two episode files into one. Because nothing is re-encoded, the operation finishes in seconds or minutes and produces a bit-perfect copy of the source media.

Use HandBrake when you need to shrink a file, convert from one codec to another (H.264 to H.265, for example), or produce a version compatible with a device that does not support the original codec. HandBrake’s output is always smaller and always at least slightly different from the source because every encode involves some information loss.

Many people use both tools in sequence: HandBrake first to transcode a large source to a manageable H.265 file, then MKVToolNix to add a subtitle track to the result without another encode pass.

Neither tool is better in an absolute sense; they solve different problems. If quality preservation is the priority and you are not trying to change codecs, MKVToolNix is the right choice.

The fastest way is mkvpropedit, which modifies the file’s header in place without a full re-mux. First run mkvinfo on your file (or use the Info tab in the GUI) to find the track IDs for your audio tracks. Then use a command like: mkvpropedit file.mkv --edit track:a1 --set flag-default=1 --edit track:a2 --set flag-default=0

This sets audio track 1 as default and removes the default flag from audio track 2. The numbers after “a” refer to the audio track order (a1 = first audio track, a2 = second audio track), not the global track ID shown by mkvinfo.

You can do the same operation in the GUI via the “Header editor” under the Edit menu. Open the file, expand the audio track entries in the tree, find the “Default track” flag, toggle it, and save.

Media players like VLC, Plex, Kodi, and mpv respect the default flag and start playback with the flagged track active. However, some players cache their own track preferences per file and may ignore the container flag on subsequent plays.

If you are building a new MKV from scratch using the Merge tab, you can set the default flag before muxing by selecting the audio track in the track list and checking “Default track” in the properties panel on the right side of the interface.

In the mkvtoolnix-gui, go to the Merge tab, add your MKV, and then click the “Output” tab at the top of the right panel. You will find a “Splitting” section where you can choose how to split: by file size (e.g., split every 4 GB), by duration (e.g., every 30 minutes), by timestamp (cut at specific timecodes), or by chapter count.

For timestamp-based splits, enter the timecodes separated by commas in the format HH:MM:SS.mmm. For example, “00:45:00.000,01:30:00.000” creates three output files: one covering the start to 45 minutes, one from 45 minutes to 90 minutes, and one from 90 minutes to the end.

From the command line: mkvmerge -o output.mkv --split duration:00:45:00 input.mkv or mkvmerge -o output.mkv --split timestamps:00:45:00,01:30:00 input.mkv. Output files are automatically numbered (output-001.mkv, output-002.mkv, and so on).

Splits happen on keyframe boundaries whenever possible. For video, MKVToolNix moves the split point to the nearest preceding keyframe, which means the actual cut may be a fraction of a second earlier than the exact timecode you specified. This is normal and necessary for the split file to be playable from the start.

If you need precise frame-accurate splits (not just keyframe-accurate), you will need to re-encode the content around each split point, which requires a tool like FFmpeg rather than MKVToolNix.

Yes. MKVToolNix has strong metadata editing capabilities through mkvpropedit and the GUI’s Header Editor. You can change the overall file title, add or remove Matroska tags (which can hold information like description, comment, content type, director, or IMDb ID), edit track names, set language codes, and toggle per-track flags like “default,” “forced,” and “enabled.”

To edit the file title in the GUI, go to Edit in the menu bar and open Header Editor. Open your MKV file, then look under “Segment information” for the Title field. Edit the value and save. The change takes effect immediately without re-muxing the rest of the file.

For tag blocks (which store richer metadata like movie title, year, director), use the Merge tab’s “Tags” section when building a new MKV, or use mkvpropedit with the –tags option to attach an XML tags file to an existing MKV.

Compared with tools like MediaInfo (read-only) or mp3tag (audio-only), mkvpropedit offers write access to MKV-specific metadata structures that other tools cannot touch.

One practical tip: if your media server (Plex, Emby, Jellyfin) is misidentifying a file, setting the correct Matroska title tag through mkvpropedit can sometimes help the server find the right metadata match without renaming the file itself.

Yes, MKVToolNix works fully on Windows 11. The official installer targets Windows 10 and 11 (64-bit), and the application runs without compatibility settings, elevated permissions, or any special configuration beyond a normal install.

As of version 97.0, the minimum supported Windows version is Windows 10 (64-bit). Windows 7 and 8 are no longer supported in current releases, though very old versions of MKVToolNix still run on those systems if needed.

The GUI uses the Qt framework, which renders natively on Windows and respects your system DPI settings. On high-DPI displays (like the Surface Pro or 4K monitors), the interface scales correctly and stays sharp without blurry scaling artifacts.

MKVToolNix also runs on macOS (12 and later, with Apple Silicon native builds available) and on most major Linux distributions via official package repositories. The same mkvmerge, mkvextract, and mkvpropedit binaries produce identical output regardless of which OS you run them on.

Windows updates do not break MKVToolNix, and the developer releases updates regularly. Checking for a new version takes seconds: open the GUI, go to Help, and click “Check for updates.”

The built-in Job Queue is the easiest way. Set up your first mux operation in the Merge tab as normal, but instead of clicking “Start muxing” click the small arrow next to it and choose “Add to job queue.” Repeat the process for each file or operation you want to batch. When all jobs are queued, open the Queue tab and click “Start all jobs.”

Each job runs sequentially and logs its full command output. After all jobs finish, the queue shows a green checkmark or a red error badge for each entry. You can re-run failed jobs individually without touching the ones that succeeded.

For large-scale automation (dozens or hundreds of files), the command-line tools are more practical. A simple Windows batch script can loop through a folder and call mkvmerge on every file: for %f in (*.mkv) do mkvmerge -o "output%~nf.mkv" "%f". On Linux and macOS, the same logic works in bash with a for loop.

MKVToolNix also supports a JSON job format for the GUI’s queue, which advanced users can generate programmatically and load into the interface rather than setting up jobs by hand.

One practical batch workflow is stripping a specific audio or subtitle track from every file in a folder. Write a mkvmerge command with --audio-tracks !2 (exclude track 2) and loop it over all your files. The whole folder is processed while you do something else.

MKVToolNix can read tracks from a wide range of container formats beyond MKV itself. Supported video containers include MKV/WebM, MP4/M4V, AVI, MOV, MPEG-2 Program Stream (VOB/MPG), MPEG-2 Transport Stream (TS/M2TS/MTS), OGM, RealMedia (RM/RMVB), FLV, and Dirac streams. Audio containers include MP3, AAC, FLAC, OGG Vorbis, Opus, TrueHD, DTS, and AC-3.

For subtitles, mkvmerge accepts SRT, SSA/ASS, HDMV PGS (from Blu-ray .sup files), VobSub (IDX+SUB pairs from DVD), WebVTT, USF, and MicroDVD format.

A common real-world workflow is pulling the H.265 video from an MP4, the DTS-HD audio from a separate M2TS rip, and an ASS subtitle from a fansub release, then combining all three into one clean MKV in a single mkvmerge pass.

Output is always MKV or WebM. MKVToolNix does not write to MP4, AVI, or any other non-Matroska container. For that, you need mkvextract to get the raw bitstream and then a different muxer (like MP4Box or FFmpeg) to package it.

When in doubt about whether a particular input file will work, just drag it into the GUI and check the detected tracks. If mkvmerge identifies the tracks, it can use them as input. The GUI makes format compatibility easy to assess without reading documentation.

In the Merge tab, add your MKV file and look at the track list below the source panel. Each subtitle track appears with a checkbox to its left. Simply uncheck any subtitle track you want to exclude from the output, then set your output path and click “Start muxing.” The output MKV contains all the original video and audio but none of the subtitle tracks you unchecked.

From the command line: mkvmerge -o output.mkv --no-subtitles input.mkv removes all subtitle tracks at once. If you want to keep some subtitles and remove only specific ones, use --subtitle-tracks 2,4 to keep only tracks 2 and 4, or use --subtitle-tracks !3 to keep everything except track 3.

Removing subtitle tracks is a common reason people use MKVToolNix. Streaming rips often come with dozens of subtitle languages that you never need, and stripping the unwanted ones can reduce file size noticeably when the subtitles are PGS bitmap-based rather than text-based.

Note that the “original” source file is never modified. MKVToolNix always writes a new output file; if you want to replace the original you need to delete or rename it manually after the mux completes successfully.

For making the same change across a folder of files without creating new output files, mkvpropedit can toggle the “enabled” flag on subtitle tracks in place, but it cannot fully remove tracks. A full re-mux with mkvmerge is the only way to permanently delete tracks from a container.