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 99.0 “Buka” 2026-05-24

## New features and enhancements

* MKVToolNix GUI: the GUI will now remember the last used directory for
selecting audio files for playback in “play audio file” program runners
separately from any other “open file”-type situations. This directory will
also default to `/System/Library/Sounds` on macOS now. Implemented by #6213.
* MKVToolNix GUI: executing actions → running programs: added new variables:
`MTX_DESTINATION_FILE_BASE_NAME` (the name without the drive letter, path or
the suffix; e.b. `/movies/A.new.hope.mkv` → `A.new.hope`) and
`MTX_DESTINATION_FILE_SUFFIX` (only the letters after the last `.`,
e.g. `/movies/A.new.hope.mkv` → `mkv`). Added examples to all the
destination file variables in the popup menu when adding variables in the
preferences. Implements parts of #6220.
* MKVToolNix GUI: executing actions → running programs: the command-line input
widget will now receive focus again after using the popup menu for adding a
variable. Implements parts of #6220.
* MKVToolNix GUI: executing actions → running programs: the variables will now
also be set as environment variables when running a program after a job
completes.
* MKVToolNix GUI: executing actions → running programs: when using the
“Execute now” button for testing the `MTX_…` variables will be set to the
current multiplexer tab’s values for easier testing. Implements parts of
#6220.

## Bug fixes

* mkvmerge: if using legacy font MIME types is off mkvmerge will now remap
legacy font MIME types present in source files into the current ones. Patch
by corticalcode via #6249.
* mkvmerge, mkvpropedit, MKVToolNix GUI’s multiplexer & header editor: on
Windows & macOS the MIME type detection will now use the FreeDesktop.org
MIME database instead of falling back to file extension-based guesses. This
matches how it works on other operating systems. This fixes e.g. OpenType
fonts being detected as the legacy type `application/vnd.ms-opentype`
instead of the current IETF RFC, `font/otf`, no matter what the “use legacy
font MIME types” settings in the preferences was set to. Fixes #6240 for
Windows; fixes #6248 for macOS. Implemented by corticalcode for macOS in
#6250.
* MKVToolNix GUI: update checker: fixed a potential attempt to read from an
invalid memory address if an error occurred when parsing the XML file
retrieved from the official MKVToolNix server.
* macOS: GUI: the default audio file for program runners of type “play audio
file” has been changed to an AIFF file as Qt’s Multimedia backend routes
through Core Audio which doesn’t support WebM/VP8/Vorbis/Opus. Existing
configurations will be updated if they point to the prior default WebM audio
file. Fixes #6209.

## Build system changes

* macOS: `build.sh`: the Qt installation is now done via `cmake –install`
instead of using classic `make` as the classic Makefiles produced by Qt’s
build system are incomplete. Patch by corticalcode. Fixes #6205.
* macOS: `build.sh`: the binaries in the DMG are now stripped of debug
symbols. Patch by corticalcode. Fixes #6206.
* macOS: `build.sh`: enabled release build optimizations for
dependencies. Patch by corticalcode. Fixes #6207.
* macOS: `build.sh`: disabled use of `pkg-config` for Qt to prevent linking
against installed non-OS libraries such as from Homebrew. Patch by
corticalcode. Fixes #6208.
* macOS: added support for notarization of a macOS disk image by an Apple
developer account. Implementation of #6212 by Touchstone64.
* macOS: patch added to make building Qt 6.11 from source possible on macOS
26.4. Patch by Touchstone64.
* macOS: additions to DMG package naming including the machine type it targets
(arm64 or x86_64) and a revision number (to support re-packaging of an
existing MKVToolnix release). For example, MKVToolNix-98.0-1-arm64.dmg would
represent the first revision of a DMG package for an Apple Silicon Mac,
containing MKVToolNix release 98.0. Implementation by Touchstone64.
* macOS: the packaging process now verifies the MKVToolNix source release
using the author’s GPG key before packaging. Implementation by Touchstone64.
* macOS: the app bundle name has been standardised by removing the version
number, so DMG packages will contain ‘MKVToolNix.app’. Implementation by
Touchstone64.
* macOS: Qt is now built without printing support, reducing the size of the
resulting DMG slightly. Implementation by Corticalcode. Implements #6230.

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