Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Online Image Editor - Online editor for images and animated gifs with multiple effects and tools
Sketch - Professional digital design for Mac.
Pixelitor - Pixelitor is a cross-platform raster graphics editor written in Java.
Adobe Illustrator - Adobe Illustrator is a vector graphics editor.
RealWorld Photos - RealWorld Photos is an free portable photo editor for Windows.