Every time I upgrade PHP in cpanel, or double-check a hosting environment, I end up back on the WordPress hosting handbook’s required extensions page. But, it’s a bit awkward to quickly reference, and it’s missing a couple of things that I have found some plugins require.
So I made this list… Alphabetical, all in one place, short description for each. I’m mostly posting this so future-me can find it again.
- apcu – In-memory key-value store for PHP
- bc – Arbitrary precision mathematics
- curl – Performs remote request operations
- dom – Validates Text Widget content, auto-configures IIS7+
- exif – Works with metadata stored in images
- fileinfo – Detects MIME types of file uploads
- filter – Securely filters user input
- ftp – Client access to files servers via FTP
- hash – Used for hashing, including passwords and update packages
- iconv – Converts between character sets
- igbinary – Drop-in replacement for the standard PHP serializer
- image – GD Graphics Library fallback for image manipulation
- imagick – Better image quality for media uploads
- intl – Locale-aware operations (formatting, transliteration, etc.)
- json – Communications with other servers, JSON data processing
- mbstring – Properly handles UTF8 text
- memcached – Distributed memory object caching system
- mysqli – Connects to MySQL/MariaDB
- opcache – Stores precompiled PHP bytecode
- openssl – SSL-based connections to other hosts
- pcre – Regular expression engine used throughout PHP and WordPress
- pdo – Database access abstraction layer; some plugins need it directly rather than mysqli
- redis – Interfacing with Redis
- shmop – Read, write, create and delete Unix shared memory segments
- simplexml – XML parsing
- sockets – Low-level BSD socket communication interface
- sodium – Validates signatures, provides securely random bytes
- ssh2 – Secure remote shell, exec, tunnelling, file transfer
- timezonedb – Timezone database for PHP’s date/time functions
- xml – XML parsing
- xmlreader – XML parsing
- zip – Decompressing plugins, themes, and WordPress update packages
- zlib – Gzip compression and decompression
One extra note: Where your PHP build offers it, enable mysqlnd as the underlying driver for mysqli (and pdo_mysql) rather than the older libmysqlclient-based driver, it tends to be faster and handles memory better. And don’t skip pdo just because mysqli is on the list, plenty of plugins expect it directly.
Bookmarking this one for next time.
