PHPCrossRef is an enhancement to PHPXref, a developer tool that’s designed to ease the process of working on large PHP projects by making it very fast and easy to browse the code documentation along with the code itself.
The Perl script works by scanning a project directory and translating the files it finds into readable cross-referenced HTML, simultaneously utilizing comments in the code to produce documentation to accompany it. The result is a collection of plain HTML files that can be read using any browser, with no supporting software required.
In January of 2006, with the approval of Gareth Watts, an online PHPXref cross-reference library was launched. Over time the online library amassed a total of 475 cross-referenced PHP projects. With 2.5 million cross-referenced library files and consuming 40 gigabytes of web server disk space, it became difficult to maintain.
Learning from this experience, work began a few years ago to streamline the generation of cross-references and to enhance the developer experience.