PHP Extensions Locations For .so Files PHP stores its .so extension files in /usr/lib/php/ then the API version of PHP. For ease of use, they have been listed here as they are not listed on any site. PHP 8.0: 20200930 PHP 8.1: 20210902 PHP 8.2: 20220829 If you need it and you can't find it, run php -i | grep API and you will see the API number: