Invision - Prototyping and collaboration for design teams
Sketch - Professional digital design for Mac.
Zeplin - Collaboration app for UI designers & frontend developers
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.