It’s very simply WordPress plugin for „nice“ shows pictures / galleries in lightbox. This plugin implements javascript library fancybox to header and footer pages created in WordPress, functions:
<ul>
<li>you can configure like original fancybox (in admin menu),</li>
<li>you can use multiple galleries on page,</li>
<li>it’s designed for NextGen Gallery.</li>
</ul>

ZMT fancybox

Plugin adds fancybox code to WP header and footer. This plugin is designed for NextGen Gallery. You can use multiple galleries on page.

shauno

Firsh

This plugin was developed to add custom fields to the excellent and popular NextGEN Gallery plugin. Simply enter the name of your new field(s), select between “input”, “textarea” or “dropdown”, and the field(s) will be automatically added to the “Manage Gallery” screens in the NGG dashboard.
Please note, you do need to add a small tag to the NGG templates to get your custom fields showing in your theme, so please do read the FAQ.
<h3>Quick note on NextGEN Gallery version >= 3.5.0</h3>
This plugin has been working untouched for about 10 years as of the beginning of 2024. But an update to NextGEN Gallery >= 3.50 broke some functionality. Thankfully it was a small 
fix to add support, so I have pushed version 1.2.5 with that support.

NextGEN Custom Fields

very usefull

Creates the ability to quickly and easily add custom fields to NextGEN Galleries and Images.

ZMT fancybox vs NextGEN Custom Fields