Creative Market - Buy and sell handcrafted, mousemade design content like vector patterns, icons, photoshop brushes, fonts and more at Creative Market.
Open Peeps - A hand-drawn illustration library.
SocialSizes - Sketch templates for sharing images & videos on social media
Control Illustrations - 108 free flat illustrations with customizable characters
Icons8 Developer API - 500k+ design assets, now available on-demand
Handsome Illustrations - Create unique illustrations for websites & applications.