This is the present list of all officially documented extensions for the PHP programming language.
Apache BCMath Brotli Bzip2 Calendars CCVS ClibPDF COM cURL DB++ IBM Db2 dBase DBM dbx DOM XML FileMaker Pro filePro GNU FriBidi FrontBase FTP GD Graphics Library Gettext GNU Multi-Precision Library Hyperwave iconv IMAP, POP3 and NNTP Informix Ingres II Instance ID InterBase IRC
LDAP Lotus Notes mailparse MCAL Mcrypt MCVE Mhash MIME Functions Ming mnoGoSearch Mohawk MS-SQL mSQL muscat MySQL Ncurses ODBC OpenSSL Oracle Ovrimos SQL PayFlow Pro PDF PDO Phalcon POSIX PostgreSQL Printer Pspell QT-Dom GNU Readline GNU Recode Regular expressions Semaphores SESAM Session Handling Shared memory SMTP SNMP SimpleXML Sockets SQLite Streams Sybase Token vpopmail WDDX Win32 API xajax XML (Xpath) XML-RPC XSLT YAZ Yellow pages / NIS ZIP Zlib Wjs
See also Extension Categorization from the official PHP Manual