MakeAppIcon - MakeAppIcon resizes and optimizes your icon designs into all formats needed for iOS and Android mobile app!
Heroicons - Beautiful, free SVG icons from the makers of Tailwind CSS.
EasyAppIcon - EasyAppIcon helps you to create your own app icons easily. Supporting Android Adaptive Icon!
App Icon Resizer - A service to resize your app icon to all needed resolutions
App Icon Maker - Create icons for mobile app stores online for free.
ResizePixel - Free image editor to crop, resize, flip, rotate and convert images online