Ouch! offers free vector illustrations for user interface, created by Icons8. These illustrations give a clean, trendy look to your designs.
DrawKit is a collection of free, beautiful, customisable MIT licensed SVG illustrations in two styles, to use on your next website, app, or project.
Create amazing illustrations by using hand-drawn sketch components. IRA Design offers a cool selection of 5 gradients and the ability to use ai., svg. or png. formats.
Foundry offers a great selection of open source SVG illustrations, created by the designers at thoughtbot. Free to use on your next project.