How to Develop a WordPress Plugin

Want to develop a WordPress plugin, but not sure where to start? In this blog, we give an overview of the skills you'll need, and discuss the basics of how to develop a WordPress plugin, and how to prepare for distribution.

Why Develop a WordPress Plugin?

Developing a WordPress plugin can be an excellent way to extend the functionality of your website or blog. WordPress, by design, is a highly customizable platform that allows for a wide range of modifications and enhancements. By creating your own plugin, you can tailor your website to meet your specific needs and preferences that may not be covered by existing plugins. Whether it's a unique feature for your e-commerce store, a custom SEO tool, or a specific content management system, a custom plugin can help you achieve your vision.

In addition, developing a WordPress plugin can also be a profitable venture. The WordPress plugin market is vast and diverse, with many users willing to pay for high-quality, reliable plugins that solve their problems. If you create a plugin that becomes popular, it can create a steady income stream. Moreover, it allows you to showcase your development skills and could potentially open up new opportunities for you in the tech industry.

Things to Know Before You Develop a WordPress Plugin

Before you dive into the wondrous world of WordPress plugins, there are a number of key things you need to know with regards to PHP, HTML and CSS, JavaScript, and the WordPress API. Let’s have a quick look at these important areas before diving into the nitty gritty of plugin development.

PHP

Before developing a WordPress plugin, it's essential to have a solid understanding of PHP. You should be comfortable with PHP syntax, variables, loops, conditionals, and functions. Knowledge of object-oriented programming (OOP) in PHP is also beneficial as it's frequently used in WordPress development. Familiarity with PHP error reporting and debugging techniques would also be invaluable during the plugin development process.

HTML / CSS

Knowledge of HTML and CSS is vital when developing a WordPress plugin as it empowers you with the ability to design and modify the layout and appearance of the plugin or the website it interacts with. HTML, the standard markup language for creating web pages, provides a structure to the web content, while CSS is used for styling the HTML elements. This knowledge is beneficial in customizing plugin interfaces, creating settings pages, or adding custom widgets. Additionally, understanding HTML and CSS is important to ensure that your plugin is compatible with various WordPress themes and for maintaining the responsiveness and accessibility of the website.

JavaScript

JavaScript and jQuery are good to know when developing WordPress plugins, as they enable dynamic and interactive features within the plugin, and enhance the user experience. With JavaScript, you can create real-time updates, form validation, interactive maps, and other complex features that PHP alone cannot achieve. Furthermore, understanding JavaScript lets you leverage WordPress's REST API, which allows plugins to interact with the core WordPress system and other plugins in a secure and standardized way. It also aids in handling AJAX calls within WordPress, enabling the plugin to communicate with the server without a page reload.

WordPress / WordPress API

Knowledge of the WordPress API is necessary when developing a WordPress plugin because it serves as the bridge between your plugin and the WordPress core system. The API provides a predefined set of functions and methods that you can utilize to interact with, modify, or extend WordPress's core functionality, without altering the core files themselves. This allows your plugin to work seamlessly with WordPress, ensuring compatibility and reducing the chance of errors. Moreover, the API also allows your plugin to interact with other plugins and themes, access databases, create settings, and customize the admin area, thereby enhancing the plugin's functionality and versatility.

Relational Databases

WordPress relies upon a relational database to store web content, web page layouts, and configuration. The WordPress API provides functions that give you easy acess to the central database. However, you’ll have to have a solid knowledge of SQL and how relational databases work in order to take advantage of this functionality.

The Most Important Thing to Consider

Without a doubt, aside from the other things we’ve covered, before plunging into plugin development, you have to have a firm grasp on what you intend your plugin to do! Otherwise you’ll be floundering about without a clear direction, like the proverbial ship without a rudder. Research your intended market carefully and come up with a compelling and unique idea that solves a pressing business problem. With a great idea in mind, you’re ready to go!

How to Develop a WordPress Plugin

Before you start plugin development, you’ll need to set up a development environment with a number of required components. This would be no different that what you’d normally want when developing any PHP application. The main difference is that in this development environment you’ll also need to install WordPress.

Here is a list of what you’ll need:

• A standard PHP installation
• A web server (e.g. Apache or nginx)
• A relational database that’s supports WordPress (e.g. MySQL or MariaDB)

Once you’ve decided to create the plugin, here are the recommended steps:

1. Fleshing out your idea and preparing a game plan
2. Set up your development environment and install WordPress
3. Write the plugin code
4. Test and debug your new plugin 
5. Package the new plugin up for distribution

Let’s have a look at each step in detail.

Step 1: Idea and Planning

The first step to developing a WordPress plugin involves identifying a need or functionality that isn't readily available or can be improved upon. Your idea should be unique and potentially beneficial to a broad range of users. Carefully map out the new plugin’s functionality and come up with a development game plan. Be sure to get feedback on your plan from respected colleagues.

Step 2: Setting Up the Development Environment

To begin development, you'll need a local environment such as XAMPP, WAMP, or MAMP. You also need to install a text editor like Geany, PhpStorm, or Visual Studio Code. Then, create a new folder in the wp-content/plugins directory of your WordPress installation, and name it after your plugin. For more information on PHP development environments and installing PHP, we offer a free course “PHP Introduction I: Installing PHP.”)

Step 3: Writing the Plugin Code

Begin your plugin with a main PHP file that includes a header comment necessary for WordPress to recognize your plugin. This file will contain the core code of your plugin. Use your knowledge of PHP, HTML, CSS, JavaScript, and the WordPress API to create your plugin's functionality.

Step 4: Testing and Debugging

It's important to thoroughly test your plugin in various scenarios to ensure compatibility and functionality. Enable WP_DEBUG in your wp-config.php file to display any errors or warnings that your plugin code might be producing. Also, don’t forget to incorporate unit testing! 

Shameless plug: we offer a hard-hitting JumpStart course on Unit Testing that's worth your time if you're not up to speed on testing.

Step 5: Preparing for Distribution

Once your plugin is working as expected, make sure to include a readme.txt file detailing the plugin's functionality, installation instructions, and other relevant information. You can then zip your plugin folder and submit it to the WordPress Plugin Directory, or distribute it independently.

Final Thoughts

Before you begin plugin development, research existing plugins to ensure you are not duplicating functionality. If you do find an already-published plugin that pretty does what you had in mind for your own plugin, consider reaching out to its developers and offering to join their team. This is a great way to gain experience, get your name in lights, and jumpstart your career.

If your objective is to make money, another thought would be to get involved in WordPress theme development. This career path involves a fascinating mix of artistic creativity with web development skills. The money is good, and companies are constantly on the lookout for attractive and highly functional themes.

Get In-Depth Training From Our Experts

If you’re still not sure about how to develop a WordPress plugin, why not get training from the best? Sign up for our course on WordPress plugin development and put your career into high gear.

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Additional Resources

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• Blog - 3 PHP Beginner Projects for New Developers
• Blog - How to Learn PHP in 2023