GitHub repository: robertleeplummerjr/Phalanger
Primary language: C#
Description: Introducing full-featured PHP runtime & compiler for .NET/Mono frameworks. Phalanger is modern open-source implementation of PHP, compatible with the vast array of existing PHP code. In addition Phalanger gives PHP-application developers lot of new possibilities; like improving the performance, allowing to use modern environments or  taking advantage of seamless .NET integration.