gentlesource

This plugin creates a short URL from the blog post permalink and stores it 
in the database. The URL is displayed below the blog post along with a link 
to twitter that passes the short URL on.
You can use all short URL services that offer an API. Here are a few:
<ul>
<li>http://melt.li/</li>
<li>http://lin.io/</li>
<li>http://unrelo.com/</li>
<li>http://bit.ly/</li>
<li>http://u.nu/</li>
<li>http://tinyurl.com/</li>
</ul>

GentleSource Short URL

Automatically shortens the blog post URL.

Shrtfly

ShrtFly is a completely free tool where you can create short links, which apart from being free, you get paid! So, now you can make money from home, when managing and protecting your links.
Use our <a href="https://shrtfly.com" title="Shrtfly" rel="friend nofollow ugc">Shrtfly – Link Shortener Plugin</a> to integrate Shrtfly on your website without touching a single line of code.
<h4>Features</h4>
<ul>
<li>Easy and Simple, you just need to add your token or API code.</li>
<li>Short thousands of URL without messing with WordPress files.</li>
<li>You can also include and exclude domain from shortening using simple panel.</li>
</ul>

ShrtFly – URL Shortener

Integrate Shrtfly - Link Shortener on your website easily without touching any code.

GentleSource Short URL vs ShrtFly – URL Shortener