KPHP (kPHP or KittenPHP) is a free PHP-to- C++ source-to-source translator, developed by VKontakte.
According to the developers, a social network's May 2013 transition to KPHP gave a twofold increase in performance. In March 2014, code compiler and related tools were released as free software on GitHub.
KPHP was conceived as not fully compatible with the PHP language to speed up compilation. It is possible to explicitly specify the types of variables and there is very limited use of the OOP. Furthermore, KPHP benefits in terms of a static analysis of the code, and uses less memory and CPU time.
K- prefix comes from the word kitten, which became a sort of tradition in the internal development of VKontakte.