Vectr - Free vector graphics editor. A simple yet powerful web and desktop cross-platform tool for everyone.
GIMP Online - Powerful graphics editor in the cloud
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Dotgrid - A simple vector illustration tool.
Promote! - Awesome Graphics, Awesome Prices, Quick and Easy to Make
Sketch - Professional digital design for Mac.