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Even More Essential Plugins for WordPress Theme Development


In the previous parts of this series, we've reviewed many of the debugging plugins that are available in the WordPress Plugin Repository. The base plugin that we've seen is Debug Bar, for which numerous extensions have been written.

In this final part, we will cover plugins specifically recommended by the Developer Plugin, and we'll add a few more that I've found useful in the course of WordPress development.

In this article, we're going to be discussing:

Rewrite Rules Inspector

Rewrite Rules Inspector plugin

If you deal with a lot of rewrite rules, then this particular plugin will assist in the following ways:

  • View a list of all your rewrite rules.
  • Filter by different sources of rewrite rules.
  • Perform a soft flush of your rewrite rules to regenerate them.
  • Check which rewrite rules match a given URL and the priorities in which they match.

Log Deprecated Notices

This particular plugin comes in handy by scanning through your project, and it lets you know if you're using any deprecated functions. It also gives details on where the deprecated function is being used and offers alternatives, making it easy to update your project.

Log Deprecated Notices plugin

Another important aspect of the plugin is that it also informs you of incorrect usage of WordPress functions. 

Theme Check

You have just finished working on a project, so what's next? Theme Check helps to determine if your WordPress theme conforms to the latest theme review standards. With it, you can run all the same automated testing tools on your theme that WordPress.org uses for theme submissions.

Theme Check plugin

RTL Tester

RTL Tester adds a Switch to RTL button in the WordPress admin bar. This makes it really easy to switch the direction of the text on the site to make sure that your site is properly internationalized for languages that read right-to-left.

RTL Tester plugin

Query Monitor

This is yet another powerful debugging plugin. It has quite a number of features that make it a personal favorite for many experienced developers. Here are some of its best features:

  • By default, Query Monitor's output is only shown to administrators on single-site installations, and super administrators on multi-site installations. In addition to this, you can set an authentication cookie which allows you to view Query Monitor output when you're not logged in (or if you're logged in as a non-administrator).
  • Query Monitor summarizes all the information about your development environment giving comprehensive details such as PHP information, MySQL information, current WordPress installation information, and web server information.
  • Even though this feature is still under development, Query Monitor can show the response from any Ajax request on the page, as long as it includes debugging information in its header. This output is then written to the developer console. At the time of this writing, only PHP errors are displayed.
  • Query Monitor also provides detailed information about database queries including affected rows, run time for queries, notifications for slow queries, queries with errors, filtering queries by calling function, and so much more. 

You can simply access all this information by clicking Query Monitor on the admin bar.


We have covered a lot in this series. At the beginning of the series, we set up our development environment in the context of WordPress by using the Developer plugin, and we then installed all the recommended plugins and enabled the debug mode by editing wp-config.php

In the second post, we focused our attention on plugins that help debug our code and easily check for errors. We primarily looked at the Debug Bar plugin as well as a number of its extensions.

In this final part of the series, we have focused on other plugins that also play a crucial role in theme development and testing. Each of these plugins will help take your project to the next level and conform to the WordPress coding standards.  

This list is not entirely exhaustive, so if you know of other plugins that you recommend, please feel free to add them to the comment list below!

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