Nexus Mods Vortex - Vortex is the new, modern mod manager from Nexus Mods.
itch.io - An online game marketplace and community.
r2modman - A mod manager for several Unity games using Thunderstore
GOG.com - DRM-free game store, selling both new and old titles. No clients required.
OpenIV - OpenIV is powerful modding tool for Grand Theft Auto IV, Max Payne 3 and Grand Theft Auto V.
Ubisoft Club - Ubisoft Club app enables you to get updates about your favorite games timely.