MKVToolNix is the one of the best collection of tools (mkvmerge, mkvinfo, mkvextract, mkvpropedit and mmg) for modifying MKV files.

The graphical user interface (GUI) of the program allows you to manipulate Matroska (MKV) files in several ways.

You can use those tools to create, split, edit, mux, demux, merge, extract or inspect Matroska files.

MKVToolnix will also work with other video formats. Such as AVI, MPEG, MP4, MPEG, Ogg/OGM, RealVideo, MPEG1/2, H264/AVC, Dirac, VC1.

And more as well as some video codecs such as VP9 video codec support – reading from IVF, Matroska, WebM files, extract to IVF files.

Moreover the program can work with audio files such as AAC, FLAC, MP2, MP3, AC3, DTS/DTS-HD, Vorbis, RealAudio. And also work with most subtitle formats including SRT, PGS/ SUP, VobSub, ASS, and SSA.

It is a cross-platform application that will work on Microsoft Windows (both 32 and 64-bit versions), Apple macOS and Linux operating systems.

Here is also the portable version which does not require installation. You just need to start the function. It can also be stored on external devices and run on any computer you have access to.

# Version 91.0 “Signs” 2025-03-16

## Important notes

* The MKVToolNix project’s source code repository, bug tracker and wiki have
been moved to [Codeberg](https://codeberg.org/mbunkus/mkvtoolnix).
* The customized MXE repository used for building the Windows variants has
been moved from Gitlab to [Codeberg](https://codeberg.org/mbunkus/mxe).

## New features and enhancements

* MKVToolNix GUI: multiplexer: added actions in the “Multiplexer” menu for
saving all currently open multiplexer tabs to a single `.mtxcfg`
file. Loading this file later will restore all tabs. Implements #3797.
* MKVToolNix GUI: multiplexer: when adding files the GUI can automatically
enable the “commentary” flag for audio and subtitle tracks if the file name
contains the word “comments” or “commentary” delimited by certain characters
(configurable). This feature is turned on by default. Part of the
implementation of #3798.
* MKVToolNix GUI: multiplexer: when adding files the GUI can automatically
enable the “original language” flag for audio and subtitle tracks if the
track’s language matches one configured by the user (configurable). This
feature is turned off by default. Part of the implementation of #3798.
* MKVToolNix GUI: multiplexer: when adding files the GUI can automatically set
several track flags based on the file name. It can now look for the same
patters in the track names, too (configurable). This feature is turned on by
default. Part of the implementation of #3798.
* MKVToolNix GUI: multiplexer: added special drag & drop zones where users can
drop files to circumvent the preferences wrt. what to do with multiple
dropped files. Each drop zone corresponds to one of the three possible
choices (add all to current settings; create one new settings & add all
there; add new settings for each file & add one file to each). This feature
is turned off by default. Implements #3796.
* MKVToolNix GUI: multiplexer: added additional special drag & drop zones
where users can drop files to add them as attachments. One of the zones will
automatically set up the dropped file to function as a cover
image. Implements #3794.
* MKVToolNix GUI: multiplexer: when making destination file names unique by
suffixing them with a running number the GUI will now also consider the
destination file names of multiplex jobs currently in the queue that are
currently running or still waiting for execution. Implements #3801.

## Bug fixes

* mkvmerge: timestamps format v3: fixed the parser; it was completely broken
for the lines containing the duration & an optional number of frames per
second. Fixes #2285.
* mkvmerge: DTS parser: if the X96 extension is present in a DTS-HD High
Resolution stream, the sampling frequency will be set to 96kHz. This was
broken when reading DTS from elementary streams & from Matroska files. Fixes
#3288.
* mkvpropedit, MKVToolNix GUI’s chapter & header editors: fixed a bug leading
to a segmentation fault when trying to replace an element at the end of the
file that’s followed by only void elements (at least one). Fixes #3802.

## Build system changes

* The bundled `nlohmann-json` library was updated to v3.11.3.

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