Curated list of awesome lists
A curated list of awesome downloadable SVG/PNG/Font icon projects
General purpose icons used everywhere.
Logos of different brands or companies or technologies.
Icons that are not general or logos, but something special.
Flag Kit - Beautiful flag icons for usage in apps and on the web.
Mapsicon - A free collection of maps for every country in the world.
Icons made out of CSS only (that are not downloadable).
cssicon - Icon set made with pure css code, no dependencies, "grab and go" icons. (Website)
icono - Pure CSS, class based icon pack. (Website)
Not open-source/free, but still awesome enough.
Heroicons - Unique set of icons for your marketing website.
Iconic - The definitive icon set designed for the modern web.