Jake Bresnehan

This plugin provides you an easy quick way to test your content looks good at various sizes.
Features of the plugin include:
<ul>
<li>Mobile view</li>
<li>Tablet view</li>
</ul>
Getting setup with the plugin
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/bXe5_BvvtxA?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>
<a href="http://web-design-weekly.com/support/" rel="nofollow ugc">Plugin Support & Feature requests</a>.

Responsive Post Preview

Adds the ability to view your posts and pages at different viewport sizes with a click of a button

robfelty

Category reminder uses javascript to assert that a category has been assigned 
to a post before publishing it. If no category is assigned, then it will 
prompt the user to assign before publishing.

Category Reminder

This plugin requires users to assign a category to each post other than "Uncategorized".

Responsive Post Preview vs Category Reminder