Artboard Studio - Online graphic design app mainly focused on product mockups.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Vectr - Free vector graphics editor. A simple yet powerful web and desktop cross-platform tool for everyone.
Sketch - Professional digital design for Mac.
Canva - Canva is a graphic-design platform with a drag-and-drop interface to create print or visual content while providing templates, images, and fonts. Canva makes graphic design more straightforward and accessible regardless of skill level.
Adobe Illustrator CC - Adobe Illustrator CC is a commercial vector graphics editor.