PHP extensions are modules that add extra functionality to PHP, such as image processing, database connections, or API communication. In Plesk, you manage these through the web interface, without needing the command line. Below you’ll find out exactly what extensions do, how to enable or disable them per domain, which modules are often needed, and what to watch out for in terms of security and performance.
What are PHP extensions?
PHP extensions are separate modules that run on top of the PHP core and offer additional capabilities. Think of GD for images, cURL for external API requests, or PDO for database communication. Some extensions are enabled by default, while others you need to activate yourself depending on the software you’re running. Each PHP version has its own set of available extensions, so when switching to a different version, it’s wise to check whether all required modules are still active.
Managing PHP extensions in Plesk
Plesk makes managing extensions easy: everything is handled through the web interface, per domain and per PHP version.
Log in to Plesk
Go to your Plesk panel, usually accessible via https://yourdomain.com:8443, and log in with your admin credentials.
Open PHP settings
Find your domain in the overview and click on it. Go to PHP Settings at the top of the screen.
Choose the right PHP version
First check whether you’re running the desired PHP version, since the list of available extensions differs per version.
Check or uncheck extensions
Scroll to the overview of available extensions and check what you need. Disable modules you don’t use.
Save the changes
Click OK or Apply. Plesk automatically reloads the PHP configuration, after which the change takes effect immediately.
Commonly used extensions and their function
- GD – scaling, editing, and generating images
- MySQLi – connection to MySQL databases
- PDO – database abstraction layer for multiple database types
- cURL – HTTP requests and API communication
- OpenSSL – encryption and SSL certificate support
- JSON – processing JSON data
- Imagick – advanced image editing
- Memcached – caching for faster pages
- opcache – caches compiled PHP code, recommended to always keep enabled
Not every extension is needed for every website. An online shop, for example, often needs GD and cURL, while a simple brochure site may do without.
Security and performance
The fewer extensions that are active, the smaller your server’s attack surface. So feel free to disable modules your application doesn’t use. Keep in mind, though, that a disabled extension can immediately cause an error if your CMS or plugin actually depends on it. It’s best to test changes in a staging environment first, or check right after saving whether your website still loads correctly.
For your organization’s daily email flow, it’s also worth looking into business email with a good security score, and when choosing a new domain, check out domain names. If you run into specific extensions you can’t find in Plesk, check the knowledge base or contact support.
Frequently Asked Questions
Can I disable extensions without any issues?
Yes, as long as your application doesn’t use the extension. Check your CMS documentation first and test after disabling to make sure everything still works.
My website shows an error after changing extensions, what now?
Re-enable the last extension you disabled and reload the page. If it still doesn’t work, contact support for help finding the cause.
Are all PHP extensions available?
The most common extensions are available in Plesk by default. If you need a specific module that isn’t on the list, please contact support so it can be looked into.
How do I know which extensions my site needs?
Many CMS platforms show a warning if a required extension is missing. You can also create a phpinfo() file to see which extensions are active.
Does enabling extra extensions affect speed?
Each active extension uses a bit more memory, but the effect is generally minimal compared to the benefits of the functionality you need.
Conclusion
With Plesk, you can easily manage PHP extensions per domain and per PHP version, without needing technical knowledge. Only enable what you actually use: this keeps your website faster and more secure. If you’re unsure which extensions are needed, consult your CMS documentation or ask support.