Open Peeps - A hand-drawn illustration library.

Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.

Control Illustrations - 108 free flat illustrations with customizable characters

Synonymful - Improve your vocabulary and communicate like a pro.

Craftwork - A collection of User Interface resources made by Craftwork

Fluent - Fluent is a people-based marketing platform that uses real-time, one-to-one interaction to create custom audiences and serve personalized ads that drive performance at scale.