Open Stage Control and Midi Device to Control Vimix
Open Stage Control is a Libre and modular OSC / MIDI controller.
ThomZenTury developed a dedicated user interface in Open Stage Control for vimix.
Check it out on github https://github.com/ThomZenTury/OSC-Vimix-UI and follow the tutorial videos:

Other tutorial: Mapping OSC with MIDI:

MIDI to OSC mapping with Chataigne
Chataigne is a powerful software for controlling and synchronizing events for shows, interactive installations or prototyping. It can for example create mapping between MIDI and OSC messages for vimix.
Thanks to Lupin3rd for developing a vimix module for Chataigne. See demo:

MIDI to OSC mapping with MidiMonster
Midimonster is an universal control and translation tool for most show control protocols, allowing to map several inputs to OSC messages for vimix.
Thanks to RKelln for sharing an example Midimonster configuration file working with an APC40 MKII (see issue #62)