nymea is an advanced open IoT gateway service written in Qt.
The main purpose is API management, but it can do much more. It is easy to attach new APIs (virtual connectors) and logically link data from any datapoint by the rule engine. Data from any source is stored locally and can be collected using the JSON RPC API.
The project is initiated and maintained by the Founders of guh GmbH in Austria, who run the startup nymea.io and deliver full-stack IoT services where this framework plays an important role.