macOS Big Sur icons - Original icons in PNG ready for download
The Noun Project - Creating, Sharing and Celebrating the World's Visual Language
Iconoir - A diverse and open-source library with 900+ icons
Freepik - More than a million free vectors, PSD, photos and free icons. Exclusive freebies and all graphic resources that you need for your projects
IconStore - Free icon packs by first-class designers
Font Awesome - Font Awesome makes it easy to add vector icons and social logos to your website. And version 5 is redesigned and built from the ground up!