OFFICIAL PAGE: Spleeter
Spleeter is a free open-source sound source separation application from Deezer Research. It comes in the form of a Python Library based on Tensorflow, with pretrained models for 2, 4 and 5 stems separation. It is a command line application so there is no GUI (graphical user interface). A couple of web-based interfaces for Spleeter are currently available at moises.ai and melody.ml, although the latter only accepts mp3 files at present.
Screenshot courtesy of Deezer Research