GoogleMapsPHP employs several open source libraries including:

• OptionSplit: Kasper Skårhøj <kasperYYYY@typo3.com>, http://www.typo3.org
• Format JSON with PHP: Dave Perrett <hello@daveperrett.com>, http://www.daveperrett.com/articles/2008/03/11/format-json-with-php/
• jQuery: http://www.jquery.org
• MarkerClusterer: http://gmaps-utility-library-dev.googlecode.com/svn/tags/markerclusterer/
• Simple JavaScript Inheritance: John Resig, http://ejohn.org/
• Marker icons: Douglas Karr, http://www.marketingtechblog.com/