List of Gateway with open API

Dear All,

Doing my thesis i would like to ask if you are aware of gateways that provide the functionality to connect with them, get access on sensor/actuator values and build on top of them some applications.

I look for an open API like that Hue and Smarthings provide but it is not clear to me which HAN provide a gateway with an open API (hopefully REST API) for remote access on data. I have checked micasavere also but it seems that they provide their own cloud service through mios

Anyway, are you aware of any gateway that provides access remotely and further provides an open API for direct access on real time data?