iOS 11 icons: Glyphs - Most demanded iOS 11 icons for free by Icons8
Pixel Icons - 6,500 unique icons designed for perfection 🚀
IconStore - Free icon packs by first-class designers
Streamline icons - The world’s largest icon pack library - 100k icons and illustrations.
Feather Icons - Simply beautiful open source icons
MakeAppIcon - MakeAppIcon resizes and optimizes your icon designs into all formats needed for iOS and Android mobile app!