phpDocumentor
A project using Symfony packages
phpDocumentor 2 is a tool with which it is possible to generate documentation from your PHP source code. With this documentation you can provide your consumers with more information regarding the functionality embedded within your source and not only what is usable to them from your user interface. Documentation generated by phpDocumentor 2 does not aim to be a replacement for conventional documentation but is rather supplemental, or reference, documentation.
Official website: phpdoc.org