neoslab

Powered Minifier allow you to reduce your page load and increase your performance by minifying your HTML source along with all the CSS and JS code present in your markup.
<h3>License</h3>
Good news, this plugin is free for everyone! Since it’s released under the GPL, you can use it free of charge on your personal or commercial site.

Powered Minifier

Honestly it's the best minifier plugin for Wordpress 

Simply Excellent

Reduce your page load by minifying your HTML source along with all the CSS and JS code present in your markup.

Matthew Haines-Young

Minification & concatenation of JS and CSS files can reduce the file size of your assets, and reduce the number of HTTP requests, helping improve page load times.
The plugin takes a manually defined list of script/style handles, and minifies and concatenates them into a single file which is then cached for future use.
Features.
<ul>
<li>Minifies & concatenates scripts and styles loaded using the WordPress dependency enqueueing system.</li>
<li>Handles scripts loaded in the header & footer.</li>
<li>Complete control – only a manually defined list of files is processed.</li>
<li>Multiple, independently processed files.</li>
<li>Minified files are only loaded if at least one component file should be loaded.</li>
<li>Compatable with localized scripts.</li>
<li>Helper tool – displays a list of scripts and styles enqueued on each page on the front end of the site.</li>
</ul>

MinQueue

Minify & Concatenate Enqueued Scripts & Styles.

Powered Minifier vs MinQueue