Unicons - Opensource vector icons and icon-font library
App Icon Maker - Create icons for mobile app stores online for free.
IconStore - Free icon packs by first-class designers
EasyAppIcon - EasyAppIcon helps you to create your own app icons easily. Supporting Android Adaptive Icon!
Streamline icons - The world’s largest icon pack library - 100k icons and illustrations.
Flat Icon Generator - Create stylish, flat icons for Android apps.