Dabuuker

Show content in a modal after page load.
Usage:
Select ‘SN Popup’ from the admin menu, then Add New. Type a name for the popup and insert any content you like. If you’re done, click Publish.
Now find a page or post you’d like to see the popup on and edit it. There should be a new metabox called ‘SN Popup’, choose the settings you want and hit Update, then view your page.
Video: https://www.youtube.com/watch?v=t6lt6v3fuEQ
To change the styling of the modal, you can override its styles in your theme’s css. Or for more advanced styling you can dequeue the default css and replace it with your own.
For reference, the default unminified version of the css is located at /plugins/sn-popup/vendor/featherlight-1.3.4/src/featherlight.css
To dequeue the old css and enqueue your own, add something like this to your functions.php:
<pre><code>add_action('wp_enqueue_scripts','remove_featherlight_css'); function remove_featherlight_css(){ wp_dequeue_style('sn-featherlight'); wp_enqueue_style('featherlight-new-css','/path-to-new-css'); } </code></pre>

Soronet Popup

themifyme

Themify Popup allows you to display beautifully responsive pop up windows on any page of your website. You can use it to showcase newsletter subscription forms, promotional announcements, or general lightbox content. You can allow popups to show on the entire site, or on certain posts, pages, categories, specific user roles, or even at specific times (so you don’t have to manually disable the popups). It’s fully integrated with the Themify Builder allowing you to design any popup layout on the frontend with the drag & drop interface and live preview.
<h4>Popup Styles:</h4>
<ul>
<li>Auto Close</li>
<li>Classic Center</li>
<li>Fullscreen</li>
<li>Time Delay</li>
<li>Slide-out Bottom</li>
<li>Slide-out Right</li>
<li>WordPress Editor Content</li>
<li>Manual Launch</li>
</ul>
Please visit this page for demos: https://themify.me/popup/.
<h4>Features:</h4>
<ul>
<li>Classic Popup – Show popup with a classic overlay with option to set the popup position</li>
<li>Slide-out – Slide the popup from either top, left, bottom or right edge</li>
<li>Fullscreen – Be extreme! Show the popup fullscreen that covers that entire screen</li>
<li>Schedule Popup – Set the date and time for when the popup with appear. Great for showing promotional popups!</li>
<li>Guests or Admins – Show popups to either guest visitors, logged-in users, or both</li>
<li>Time Delay – Set exactly (in seconds) when the popup will appear</li>
<li>Page Viewed – Show popup when viewer has visited a certain number of pages on the site</li>
<li>Scroll Position – Show popup when viewer scrolls to certain position of the page</li>
<li>Launch Popup Button – Insert a button to launch popup manually (like a lightbox link button)</li>
<li>Popup Dimensions – Enter custom popup dimensions for each popup and set custom overlay color</li>
<li>Animation – Over 40+ animations to choose for opening and closing popup transitions</li>
<li>Show Popup Once – Do not show the same popup to the same visitor for a certain number of days</li>
<li>Auto Close – Close popup automatically after a number of seconds it is opened</li>
<li>Mobile Disable – Options to disable popup on mobile devices (to avoid SEO mobile penalty by Google)</li>
<li>Themify Builder Integration – Design any popup with Themify Builder or the free Builder Lite plugin. It comes with a few sample popup layouts</li>
</ul>
Check out our documentation page here – https://themify.me/docs/popup-documentation

Themify Popup

I have been hunting for a simple, straightforward popup plugin for months. This one works perfectly for my needs; and it does not have conflicts with my themify.me themes.

Very helpful plugin

Turn visitors into subscribers and increase sale conversions! Use Popup to show newsletter forms, promotions, or lightbox content.

Soronet Popup vs Themify Popup