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 by guh GmbH, the company behind nymea.io. The purpose of it is to deliver full-stack IoT services and the nymea framework plays a key role into that.