Nicolas Juen

This plugin generate images with attributes for the responsive images in your content. 
Choose the breakpoints and the sizes associated. 
The next images you will insert and the elements generated with the wp_attachement functions will begenerated with the right attributes.
Contribute on https://github.com/Rahe/Simple-responsive-images 
Based on http://www.grahambird.co.uk/lab/doubletake/ for javascript

Simple Responsive Images

This plugin generate images with attributes for the responsive images in your content.

PStevenson

In short, this plugin modifies “the_content()” and the post thumbnail function by re-rendering the images with use of the SRCSET attribute. Other plugins do this for templated images, but not in the content region itself. This plugin will automatically work with any previously uploaded images as well.

Post Script Responsive Images

SRCSET responsive images on wordpress for content images.

Simple Responsive Images vs Post Script Responsive Images