What is a free prototyping application (not for mobile phones and tablets) for mac?

Question

Software and Internet Services

For the designer, you need to draw the layout of the elements for the web page so that he draws the design for it. I found online services on the Internet, but they are all in English and in most cases they are paid. I need something so that I can download it to my macbook and calmly draw for the designer and send him a picture