Iconoir - A diverse and open-source library with 900+ icons
Feather Icons - Simply beautiful open source icons
Squid.ink Flat Icon Pack - 2000 handcrafted, pixel-perfect & ready-to-use icons
LineIcons - 2000+ line icons for designers and developers
Flat Icons - 20,000 unique, customizable icons with free lifetime updates
IconShock - Over 2 million free icons in 400+ icon sets over 30 styles