APC &reftitle.intro; The Alternative PHP Cache (APC) is a free and open opcode cache for PHP. Its goal is to provide a free, open, and robust framework for caching and optimizing PHP intermediate code. &pecl.info.dead.git; &url.apc.source;. Alternatives to this extension are OPcache, APCu, Windows Cache for PHP and the Session Upload Progress API. &reference.apc.setup; &reference.apc.constants; &reference.apc.reference; &reference.apc.apciterator;