Installing PHP Extensions and Complex Libraries Across Various Operating Systems and Control Panels

PHP extensions add abilities to PHP itself, such as image handling, international text or database drivers. PHP libraries are plain PHP code that your project pulls in with Composer. This guide explains the difference, shows how to install extensions on the common Linux systems, Windows and the main control panels on a server you manage, and explains what you can and can't do on shared hosting.

1. Extensions and libraries are different things

When an application says "requires the intl extension", that is a server job. When it says "run composer require", that is a project job. Libraries often depend on extensions: a line such as "ext-intl": "*" in composer.json means the server must have intl.

2. Check what is already loaded

php -v                  # the command-line PHP version
php -m                  # extensions loaded by command-line PHP
php --ini               # which php.ini files are read

The website can use a different PHP version or configuration from the command line. Confirm with a small test page, then delete it:

<?php
foreach (['intl', 'gd', 'mbstring', 'pdo_mysql', 'zip'] as $ext) {
    echo $ext, ': ', extension_loaded($ext) ? 'loaded' : 'missing', "\n";
}

3. Ubuntu and Debian

sudo apt update
sudo apt install php-intl php-gd php-mbstring php-zip     # for the default PHP version
sudo apt install php8.3-intl                              # or name the version explicitly
sudo systemctl restart php8.3-fpm                         # with Nginx or Apache + PHP-FPM
sudo systemctl restart apache2                            # with Apache's PHP module

Match the version prefix to the PHP you actually run (php -v). Mixing versions is the most common reason an "installed" extension doesn't load.

4. AlmaLinux, Rocky Linux and Fedora

sudo dnf install php-intl php-gd php-mbstring php-zip php-pdo php-mysqlnd
sudo systemctl restart php-fpm
sudo systemctl restart httpd          # or nginx

On version 9, a newer PHP than the default comes from a module stream: sudo dnf module list php, then sudo dnf module enable php:8.3. Version 10 dropped module streams, so check dnf list php for the version it ships. Some extras come from the EPEL repository (sudo dnf install epel-release). CentOS Linux is end of life; use AlmaLinux or Rocky Linux instead, and dnf in place of yum.

Extensions not packaged by your distribution can be built from source. PECL has long been the tool for this; the PHP Foundation's newer installer, PIE, is the recommended route for current PHP versions. Both need build tools and PHP development headers (php-devel or php8.3-dev). The full Linux walkthrough is in enabling essential PHP extensions on a VPS.

5. Windows

The official Windows builds of PHP ship most extensions as DLL files in the ext folder; you enable them in php.ini:

Download extra extensions only as DLLs built for your exact PHP version, architecture (x64) and thread-safety type (NTS for IIS with FastCGI).

6. Servers with a control panel

On a server with a control panel, use the panel's own tool so updates don't undo your change.

All three need administrator (root) access. For DirectAdmin details, see installing and managing PHP extensions in DirectAdmin.

7. Libraries with Composer

Composer installs the libraries a project needs and generates an autoloader:

composer require guzzlehttp/guzzle
composer install --no-dev --optimize-autoloader     # for production

<?php
require __DIR__ . '/vendor/autoload.php';

Commit composer.json and composer.lock, not vendor, to version control. On production, run composer install, never composer update, so you get exactly the versions you tested. See installing Composer and using it to manage PHP libraries.

8. On Domain India shared hosting

On our cPanel and DirectAdmin shared hosting the PHP builds are shared by every account on the server:

• You can't install extensions. A php.ini or .user.ini line such as extension=redis.so does nothing, and dl() is disabled. The common extensions are already loaded.
• You can choose the PHP version. cPanel offers PHP up to 8.5, with 8.3 as the default for new accounts; DirectAdmin offers up to 8.3. Each version has its own set of extensions.
• You can't run Composer on the server. It needs functions such as proc_open, which are disabled on shared hosting, even over jailed SSH. Run composer install on your computer or in CI with the same PHP version, then upload the project with its vendor folder.
• Some functions are off even when the extension is loaded. See PHP disabled functions on shared hosting.
• Windows (Plesk) hosting supports PHP alongside .NET; ask support about a specific extension.

If an extension is missing, open a ticket with the domain, PHP version and extension name, and support will tell you whether it can be provided or needs a VPS. Some, such as Redis or MongoDB drivers, need a background service that shared hosting doesn't offer.

For full control over PHP and its extensions, a Domain India VPS gives you root access. It is self-managed, and cPanel isn't offered on it; the optional panels are listed on the VPS page.

Prices on the cards are live Domain India list prices and exclude 18% GST.

Frequently asked questions

Ready to set up PHP your way? Compare VPS plans for full control, or open a support ticket with the extension name and PHP version if you're on shared hosting.