Crossover is made by Codeweavers who are the devs of Wine.

They're also responsible for Proton in collaboration with Valve. Codeweavers CTO has been project lead of Wine for three decades.

	▲	ekianjo 21 minutes ago \| parent [-]
		> responsible for Proton Part of Proton only. Proton is a mix of various projects. Esync, Fsync, Wine, DXVK, and more... > Codeweavers CTO Yes Julliard is very famous and key to the project