The Noun Project - Creating, Sharing and Celebrating the World's Visual Language
Heroicons - Beautiful, free SVG icons from the makers of Tailwind CSS.
Nucleo - Commercial vector icons and accompanying apps to manage and customize them.
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!
Tabler Icons - 550+ free fully customizable SVG icons