I'm the founder of Icons8, a freemium icon library for UX designers and UI developers.
Power users download all our icons offline. In this case, power users is not a euphemism for 'paid users'; the app is free.
We also create plenty of side projects. They all are free, and some are open source:
- omg-img — Icons by URL. http://png.icons8.com/home will get you an icon of home
- Lunacy - Sketch viewer for Windows
- Line Awesome - modern outline icons; compatible with Font Awesome
- IconPharm — neat web app with 9000 open source icons from Google Material and other popular libraries