Ikonate – fully customisable & accessible vector icons

Design
iconoteka
N. Mockups
ICONSVG - Quick customizable SVG icons
Unicons
Sets - Privacy & Security
Eva Icons - beautifully crafted Open Source UI icons for common actions and items.
Better Icon Design in 6 Easy Steps – The Iconfinder Blog
Evericons
BoxIcons
Icons - UWP app developer
My Mac app icon design workflow
Smashicons - Iconfinder.com
Iconjar & Sketch Vector OS X Cursors
Free svg background generator
Free Vector Illustrations to Class Up Your Design | Icons8 Illustrations
Customizable illustrations for digital projects and printouts
scribbbles
Streamline Lab
HEY email
Img 0310
Storytale — High-class web illustrations under simple subscription
Blush, Illustrations for everyone
Height - Work together better
NetNewsWire
Feedbin
Air - The whiteboard for your team’s images and videos
Vector Creator — Create engaging illustrations in-browser for free
Fresh Folk
Humaaans: Mix-&-Match illustration library