The official Cortical.io Retina PHP SDK aims to simplify interaction with the REST API. To develop, users need an Api key, PHP version 5.6.3., and PHPUnit, a library that runs integration tests. Authored by Peter Weller on GitHub.
Affectiva's emotional measurement API has been around for a couple of years now. Affectiva has seen adoption by marketers, publishers, gaming companies, and chat services. However, Affectiva believes it can greatly expand the use case scenarios by offering its service at no charge to startups.