MKVToolNix — The Complete Guide: Merging, Splitting and Editing Tracks in MKV Files Without Re-Encoding
MKVToolNix is an open-source (GPL-2.0) toolkit for working with Matroska (MKV) files, with a convenient graphical interface and command-line tools. It is free for any use including commercial. The developer has announced that macOS builds and support end in the second half of 2026; development continues for Windows and Linux.
MKVToolNix
Moritz Bunkus
An open-source toolkit to create, alter and inspect MKV files: merge, split, add subtitles and audio tracks, without re-encoding.
Get it from the vendorWhat you get
- mkvmerge — build an MKV file from other media files and join several clips into one file.
- Splitting — break a long recording up by time or by size.
- Track management — add and remove audio, subtitle and chapter tracks, and change names and languages.
- mkvextract — pull an audio or subtitle track out of the file.
- mkvinfo — show the structure of the file and its tracks.
When it is useful
MKVToolNix suits organising recordings of lectures, meetings and long documentation: join the parts of a recording that was interrupted, add chapters by topic and attach a subtitle file. Since nothing is re-encoded, the operation is fast and quality is preserved. Limitation: the output format is MKV, and the tool is neither a video editor nor a re-encoder.
Related tools
For visual lossless cutting in any format — LosslessCut. For converting to another codec or format — FFmpeg or HandBrake.
LosslessCut
Mikael Finstad
Cut and join video without re-encoding — fast and with no quality loss, for drone footage, inspections and recordings.
Get it from the vendor
FFmpeg
FFmpeg project
A command-line engine for encoding, converting, cutting and compressing video and audio in almost any format, and the basis of most free video tools.
Get it from the vendor
HandBrake
HandBrake team
Compress and convert large video files — screen recordings and site videos down to a shareable size.
Get it from the vendor
VLC media player
VideoLAN
An open-source media player that plays almost every video and audio format, with basic file conversion, no ads and no tracking.
Get it from the vendorThe bottom line
The standard tool for anything to do with MKV files: fast, precise and with no loss of quality.