For people familiar with the on-line NASA/JPL Horizons API, these PHP programs serve as a proof-of-concept demonstrating some of the kinds of custom software that one can build with PHP around the Horizons API.  All the programs are in the public domain and come with their complete commented source code and any related images.

Some of the programs are meant to be tutorials, but some are also starting templates which can be expanded upon and customized to your own specifications.