Streamline icons - The world’s largest icon pack library - 100k icons and illustrations.
Zwicon - A simple, carefully designed collection of icons
Nucleo - Commercial vector icons and accompanying apps to manage and customize them.
Flat Icons - 20,000 unique, customizable icons with free lifetime updates
Vivid JS - A highly customizable, open source SVG icons library
IconStore - Free icon packs by first-class designers