Qtractor is a free and open source multi track non linear audio sequencer for Linux. You can use it for any audio and MIDI files for recording also. Supported audio files are OGG, MP3, WAV, FLAC, AIFF and more via libsndfile library.It uses Jack Audio Connection Kit for audio and the Advanced Linux Sound Architecture for MIDI files. It is released under GNU General Public License (GPL) version licence. It is written in C++ and Qt. It comes with build in audio mixer and monitor controls and connection patchbay control. Some other features are Unlimited effect inserts per track or bus, tempo map and MIDI clip editor.