LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
CThruView Transparent Image Viewer - CThruView is a free transparent image viewer that allows mouse clicks to go through the image.
OmniGraffle - OmniGraffle is for creating precise graphics like website wireframes, an electrical system designs, or mapping out software class.
PixelPerfect - Allows developers to put a semi-transparent image overlay over the top of the developed HTML and...
draw.io - Online diagramming application
Osiva - Osiva" is an acronym that stands for "Overly Simple Image Viewing