Joost de Valk

Yoast

Allows you to easily find the custom fields (including hidden custom fields) and their values for a post, page or custom 
post type post.
Just go to Tools – Custom field finder, enter the post ID of any post and you’ll see all the custom fields. This includes 
the custom fields that start with an underscore ( _ ) that are normally hidden from the custom fields interface.

Custom field finder

Allows you to easily find the custom fields (including hidden custom fields) and their values for a post, page or custom post type post.

Duke

Shambix

thaikolja

akforsyt

This plugin allows you to export your posts to CSV or XLS file, through a simple link/button, from either backend or frontend. 
Make sure you are using PHP 7.3+, if you see any errors, older versions will not be supported anymore. The plugin has been tested up to PHP 8.1.
Supports
<ul>
<li>any custom post type</li>
<li>custom post status</li>
<li>custom taxonomies</li>
<li>custom fields</li>
<li>WooCommerce products, orders, status, categories and fields</li>
<li>export only current user posts</li>
<li>export specific user ID posts</li>
<li>export specific post IDs</li>
</ul>
You can set the default post type, with its taxonomies and custom fields, that you wish to export, from the Settings page.
After that, anytime you will use the urls <code>https://yoursite.com/?export=csv</code> for a CSV file, or <code>https://yoursite.com/?export=xls</code>, you will get that post type data.
“You must choose the post type and save the settings before you can see the taxonomies or custom fields for a custom post type. Once the page reloads, you will see the connected taxonomies and custom fields for the post type.”
If you want to export from a different post type than the one saved in these settings, also from frontend, use the url <code>https://yoursite.com/?export=csv&post_type=your_post_type_slug</code> for a CSV file, or <code>https://yoursite.com/?export=xls&post_type=your_post_type_slug</code> to get a XLS.
Please check the <a href="https://wordpress.org/plugins/simple-csv-xls-exporter/#faq" rel="ugc">Plugin’s FAQ</a> for all possible options and available custom parameters you can use.
When opening the exported xls, Excel will prompt the user with a warning, but the file is perfectly fine and can then be opened. Unfortunately this can’t be avoided, <a href="http://blogs.msdn.com/b/vsofficedeveloper/archive/2008/03/11/excel-2007-extension-warning.aspx" rel="nofollow ugc">read more here</a>.
<h4>Questions?</h4>
Check the FAQ before opening new threads in the forum!
<blockquote>
Contact me if you want a custom version of the plugin, for a fee (contact form at <a href="http://www.shambix.com" rel="nofollow ugc">shambix.com</a>).
</blockquote>
<ul>
<li><a href="https://github.com/Jany-M/simple-csv-xls-exporter" rel="nofollow ugc">Current Plugin on Github</a></li>
</ul>
<h4>Credits</h4>
<ul>
<li><a href="https://github.com/mediebruket/custom-csv-exporter" rel="nofollow ugc">Last forked plugin’s version</a></li>
<li><a href="https://github.com/ethanhinson/custom-csv-exporter" rel="nofollow ugc">Original plugin’s version</a></li>
</ul>

Simple CSV/XLS Exporter

Simple CSV/XLS Exporter does exactly what it is supposed to do: exporting specified content to CSV or XLS files. Nicely embedded into the dashboard, works right out of the box, no annoying limitations to force users to buy any premium version. I couldn't find any negative thing.

Clean, efficient, reliable

WP 6.0 + theme 2021 + no plugins + PHP 7.4

Not bad but it does not work with clear WP installation.

Export any content to CSV or XLS, through a link/button, from backend / frontend. Supports custom post types, WooCommerce, custom taxonomies, post sta …

Custom field finder vs Simple CSV/XLS Exporter