serializer
Library for (de-)serializing data of any complexity; supports XML, JSON, and YAML.

object-routing
Library for generating routes based on objects.

twig.js
The flexible, secure, and high-performance templating engine for Javascript.

PHP-Manipulator
Library for Analyzing and Modifying PHP Source Code.

parser-lib
Library for Writing Recursive-Descent Parsers.

PHP-Collection
General Purpose Collection Library for PHP.