Feather Icons - Simply beautiful open source icons
Iconoir - A diverse and open-source library with 900+ icons
LineIcons - 2000+ line icons for designers and developers
Squid.ink Flat Icon Pack - 2000 handcrafted, pixel-perfect & ready-to-use icons
Flat Icons - 20,000 unique, customizable icons with free lifetime updates
IconStore - Free icon packs by first-class designers