This is a wordpress plugin called Visual Composer. If I remember well it costs 17$. Many wordpress themes sold at 49$ have it incorporated. Perhaps they have bulk sale agreement with the plugin authors. I saw most high end, premium WP themes selling around 50$ had this thing as an included feature, which a customer would not want to part with.
It does not have to be free for zc, but as long as solid, proven similar plugin at similar price available for zc, I'll be one happy user. This visual drag and drop plugin allows good responsive capacity.
And Google is already sending warning emails to websites saying sort of "your website is not responsive, it will be accordingly ranked low for mobile users. You'd better do something.... In order to do that look at how to make websites responsive google tutorial, blah ... blah".
If you installed google analytics, you may get this sent to u.
So responsiveness is a must.
Recently I bumped into conversionXL.com which sort of suggests research based tips for websites. An example is customers abandon shopping carts less when the checkout process is simpler and with less steps. (Many other scientifically proven tips, like: a little brighter, bigger call to action button or buy it now button etc. ) This feature and the above responsive and DIY design plugin might help zc to be stronger.
