Handsome Illustrations - Create unique illustrations for websites & applications.
Google Open Source - All of Googles open source projects under a single umbrella
Control Illustrations - 108 free flat illustrations with customizable characters
Opensource Builders - Find open-source alternatives to commercial apps
Ouch! Illustrations by Icons8 - Professional, perfectly matching, and customizable illustrations for any designs
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.