A few years ago, WordPress’ popularity was limited to the blogger community. Later, as developers took an interest in the power of content management systems (CMS), WordPress became the go-to space for complex website creation.

Nowadays, we can develop any kind of website using WordPress. In fact, through continuous evaluation, WordPress came up with advanced plugin customization and themes to curate an indispensable website.

Today, over 30% of the websites are powered by WordPress due to its flexible and simple features. The unparalleled level of customization that WordPress provides helps a lot of developers by making their lives simple and easy.

In a developer’s journey, there are multiple junctures where they might have to choose one between the many options laid out in front of them. In one such case, a developer ponders over the choice between plugin development and theme customization. Both these choices are equally important and beneficial, but sometimes, a developer might have to choose just one.

Let’s take an example if you want to add a custom price to the checkout page based on some product quantity using dynamic calculation using the Woo-commerce plugin. Also, there is no plugin available which can fit your requirement. There are often two ways to achieve this functionality. You can either add the code in the activated theme or you can develop a new plugin that will have all the functions that you need.

Some developers think that adding the code in functions.php is easy and the right way to go. However, this is not true; you can also develop a plugin depending on your needs. In this article, we will discuss the pros and cons of  Plugin Development vs functions.php file, and find which method is better.

Write Custom Code In functions.php File

Writing code in the theme’s functions.php file is always simple and easier to do when compared to developing your plugin. Some developers often use custom code in themes.

While this File can work as your plugin, but the bottom line remains that it is not a plugin.

We know that themes are mainly used for design, fonts, and layout. We can also use themes as some basic customization.

Let’s now discuss the advantages and disadvantages of adding code to functions.php file.

Benefits Of Adding Code To functions.php Or In Theme

  • Uses code to change theme related changes only, like; Featured image function, excerpts length, Widgetized areas, etc.
  • Admin functions.php can easily change the files from WordPress. You cannot change this in the plugin because once you update the plugin, it’ll overwrite the changes and you’ll have to start from scratch.
  • You can add, change, and delete any of the snippets in the file.
  • You can easily check the code and understand properly.
  • Sometimes in the plugin, it is hard to find any snippets, whereas in the theme you can easily find it.
  • It will save a lot of time for the developers.
  • You can include multiple files for different theme functionalities.
  • It is easy to work on CSS if your functions are in the themes.

Challenges Of Adding Code To functions.php Or In Theme

  • The functionality is limited to the theme you are working on. So, the code will not work for other themes, once you switch it.
  • Once you update the theme, all changes will overwrite it, unless you have a child theme.
  • It is hard to understand the code because you have created a large functionality using the theme.
  • It is difficult to disable/enable the functionality from the admin. Whereas, the plugin allows that with ease.
  • Themes are a framework, as you add more plugins, it becomes more functional. So, it is better to use plugins.

There are many ways you can customize the code into your site. However, it will never replace the WordPress Plugin. A plugin and adding code snippets to your functions.php file will have the same result on performance.

Plugin Development

There are many plugins available in WordPress to make a developer’s life easy. However, it is not possible to get plugins for some complex functionality. In such a case, we can develop our plugins.

Let’s take the above pricing customization example. For these kinds of requirements, you may write code in functions.php. However, if the functionality is complex, I would recommend developing your plugin.

Plugins can be used in any of the websites, whereas theme customization will work for the particular theme. The main benefit of developing the plugin is that you can always use the hooks to extend functionality to the plugins.

Benefits Of Developing Plugins

  • A WordPress plugin does not depend on the theme. We can install Plugins in any of the WordPress sites.
  • Plugins will not have any performance issue if it is the same code as functions.php file.
  • Plugins are always easy to disable, update, or reinstall as needed.
  • You can easily identify the plugin functionality from the plugin’s description.
  • You can add your custom style and scripts in the plugin. Which will not be included when the plugin is deactivated.
  • You can use plugin’s shortcode for the functionality in the pages or posts.
  • Plugins allow us to customize the WordPress admin & dashboard. You can always disable the same.
  • If there is any update or changes to the plugin, it might not affect your site unless you have an error.
  • If you have some customized code for the theme using plugins, it will work the same.
  • As I said in the above point, you can always deactivate the plugin if it stops working or has any issues.
  • You can develop the plugin using OOPS concepts which will secure the plugin in a better way.
  • Hooks are always better to use to extend the functionality via theme files.
  • To track/debug the issue simply deactivating the plugin
  • You can enable/disable features if you suspect there is conflict.
  • Once you create a complex plugin, you can upload it to the WordPress plugin repository and sell it to customers who need it.

Challenges Of Developing Plugins

  • It will take more time and effort to develop the plugin for small functionality.
  • It may conflict with other plugins with the same name functions or methods.
  • May not be compatible with all the themes.


So, as we discuss some of the advantages and disadvantages above, we can get the idea of both features. If there are some theme-related changes like excerpt length change, image size, etc., you can use functions.php file to add the code.

On the other hand, if some complex customization needs to be added to your website, it is recommended to develop a plugin instead of writing code in the theme. It is easier to manage plugins instead of changing large files.