Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
Sketch - Professional digital design for Mac.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
Adobe Illustrator CC - Adobe Illustrator CC is a commercial vector graphics editor.
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.