MakeAppIcon - MakeAppIcon resizes and optimizes your icon designs into all formats needed for iOS and Android mobile app!
Free Stock Images - Handpicked collection of free images (no AI!)
Bjango App Icon Templates - App icon templates for PS, Ai, Sketch and Affinity Designer
Responsive Pixel Art - It's exactly that... responsive pixel art 🙃
favicon-generator.org - Generate icons for website and mobile app stores.
Pixel Pix - Turn your photos into pixel art