Jonathan Desrosiers

Linchpin

Aaron Ware

<blockquote>
Similar functionality has been developed for the <a href="https://developer.wordpress.org/themes/advanced-topics/customizer-api/" title="Theme Customizer API" rel="nofollow ugc">Theme Customizer API</a> and was <a href="https://make.wordpress.org/core/2016/01/28/previewing-site-responsiveness-in-the-customizer/" rel="nofollow ugc">merged into WordPress core as of version 4.5</a>. This plugin will automatically deactivate when you install WordPress 4.5.
</blockquote>
When viewing the front end of the site, a “Responsive” button is added to the WordPress Toolbar. Clicking that will toggle an overlay with your website presented in various sizes for easy responsive design testing.
This can be useful both during theme development, and when writing content to verify it will be presented properly.
This plugin is a heavily modified version of <a href="http://mattkersley.com/" title="Matt Kersley's" rel="nofollow ugc">Matt Kersley’s</a> <a href="http://github.com/mattkersley/Responsive-Design-Testing" title="Responsive Design Testing" rel="nofollow ugc">Responsive Design Testing</a>.

Responsive Page Tester

Gives users with content creating permissions the ability to preview their site in a responsive testbed.

Vladimir Prelovac

Theme Test Drive WordPress plugin allows you to safely test drive any theme on your blog as administrator, while visitors still use the default one.
It happens completely transparent and they will not even notice you run a different theme for yourself.
Best part is you can even set the testing theme options (if it has them) in the Admin panel while you are testing the theme.
You can also preview any theme by adding “?theme=xxx” to your blog URL. For example http://www.myblog.com/?theme=Default
Plugin by Vladimir Prelovac. Managing more than one WordPress sites? Check out <a href="https://managewp.com" rel="nofollow ugc">ManageWP</a>.
<h3>Credits</h3>
Some of the functions of Theme Test Drive plugin came from other plugins. So I can at least thank these people:
<ul>
<li><a href="http://boren.nu/" title="Ryan Boren" rel="nofollow ugc">Ryan Boren</a> for his <a href="http://dev.wp-plugins.org/wiki/ThemeSwitcher" title="Theme Switcher" rel="nofollow ugc">Theme Switcher</a> plugin</li>
<li><a href="http://andufo.com" title="Andres Santos" rel="nofollow ugc">Andres Santos</a> for his <a href="http://andufo.com/proyectos/plugins/wp-websnapr"" title="wp-websnapr" rel="nofollow ugc">wp-websnapr</a> plugin</li>
<li><a href="http://www.deliciousdays.com/" title="Oliver" rel="nofollow ugc">Oliver</a> for his <a href="http://www.deliciousdays.com/cforms-plugin" title="cforms II" rel="nofollow ugc">cforms II</a> plugin</li>
<li><a href="http://www.plaintxt.org/" title="Scott" rel="nofollow ugc">Scott</a> for his excellent readme.txt file</li>
<li><a href="http://www.websnapr.com" title="WebSnapr" rel="nofollow ugc">WebSnapr</a> folks for their service</li>
</ul>
Thanks.
<h3>License</h3>
This file is part of Theme Test Drive.
Theme Test Drive is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Theme Test Drive is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Theme Test Drive. If not, see <a href="http://www.gnu.org/licenses/" rel="nofollow ugc">http://www.gnu.org/licenses/</a>.

Theme Test Drive

Safely test drive any theme as an administrator, while visitors use the default one.

Responsive Page Tester vs Theme Test Drive