olivierognn

With this plugin you can use the shortcode [twitter-author] to add a nice preview of the author’s twitter profile in your post. The only requirement is that the author has indicated his twitter nickname in the user management page of WordPress.

twitter-Author-follow

This plugin helps you to show the author twitter profile in your posts using the shortcode [twitter-author]

demixpress

This plugin makes it even easier and better to display <a href="http://addthis.com" rel="nofollow ugc">AddThis</a> tools for your WordPress site, including share buttons, follow buttons and recommended contents.
To make this plugin to work:
<ol>
<li>You must have an AddThis account.</li>
<li>You CAN NOT use other AddThis plugins.</li>
</ol>
About Social Sharing Optimization
This plugin doesn’t do anything to optimize the social sharing results, if you need this, try a related plugin, such as:
<ul>
<li><a href="https://wordpress.org/plugins/wpsso/" rel="ugc">WordPress Social Sharing Optimization</a></li>
<li><a href="https://wordpress.org/plugins/wonderm00ns-simple-facebook-open-graph-tags/" rel="ugc">Facebook Open Graph, Google+ and Twitter Card Tags</a></li>
</ul>

(dp) AddThis

Makes it even easier and better to display AddThis tools (share buttons, follow buttons and recommended contents) on your WordPress site.

twitter-Author-follow vs (dp) AddThis