From the official website of the project You will be able to find a multitude of information and documentation regarding this tool, and also a download area with the different releases and different packages for various distributions supported by this program. I'm talking about the graphical and open source utility MKVToolNix, which has now reached stable version 18.0.0 with notable new features and performance improvements over previous versions.
MKVToolNix is available for other operating systems, since it is multiplatform, but that does not interest us here, simply to say that it is a very interesting app for all those who want to manipulate your videos in MKV format (Matroska). After some development time, it now comes with updates to improve its stability, reliability and performance, especially for AVC and HEVC ES thanks to the implementation of support for copying without using so much memory and enabling stack protection when compiling the code with new versions of Clang.
But those are not the only novelties of this new version, it also comes with new functionalities, full support for MinGW 7.2.0 and Clang 3.8.0 compilers or later. There are also changes regarding the multiplexer, a simple GUI to do all operations graphically, and other bug fixes that were in previous versions. So everything interesting about MKVToolNix is now updated and with more force with this new release ...
What can I do with this software? Well, the truth is that it has a large number of tools available for the Matroska format and developed by Moritz Bunkus. With them we will be able to create, modify and inspect MKV video files such as mkvmerge, mkvinfo, mkvextract, and mkvpropedit that work in a non-graphical way, that is, from the CLI, but for the laziest as I have said, it has a graphical interface available called MKVToolNix GUI that you can also download from the link I left at the beginning ...