This plugin hasnt been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.
This simple WordPress plugin inserts smart jQuery code to your website header and makes old, non-responsive web sites automatically responsive. It doesn’t use Bootstrap, nor any responsive grid system.
This plug-in worked well in creating a responsive version of my website built on the Avada theme, but when activated it blew-up the size of the full site to a view that looked about 3x zoomed in. I won't be able to use it if it has this effect when viewing the site on a laptop. Hoping for a fix as it worked really well otherwise.
It works really good at first sight, now my whole site is responsive.
One thing is that when you scale down on a PC for instance, the whole site scales with it, including text, making the text to small to read. Then when you try to zoom into the text the plugin registers that as further scaling down the site, at that point it activates the mobile feature.
The only thing this plugin needs is an allowance for zooming per device (to a customizable amount maybe).
Anyway, it is a good start for me so far!