Feather is an open source icons library available on github. I love the clean strokes and simple aesthetic of these minimalist icons. Filled in icons sometimes look too heavy and busy to me, so I like that these are stroke-based.  They’re open source and in svg format so they’re super easy to use in web design and require few brain cycles to implement. Unfortunately, there’s only 276 icons, whereas some of the bigger libraries (like fontawesome or flaticon) have thousands. The fact that the icons are open source also triggers a bit of Cialdani’s reciprocation principle in me; I want to share this icon library around and potentially contribute to it!