As we are striding into the initial era of the Internet of Things (IoT), a key question is how we make the most of IoT for all stakeholders, including platform providers, IoT application developers, end-users, large and small organizations (such as city councils, enterprises) that wish to provide better services, and manufacturers of smart devices. The amount of smart devices immersed in everyday life, from manufacturing to clothing, is growing every day in terms of power, processing and network connectivity. The sheer size and variety of contextual data that they produce, along with the actions they can take on their environment, is enormous. It remains to be answered how all this potential will come to bear; the 3rd International Conference on IoT as a Service (IoTaaS) aims to contribute to the discussion on the challenges posed by these trends. The "Everything as a Service" deployment paradigm will enable the easy adoption of IoT based services and applications by end-users, while forcing providers of smart objects and middleware platforms to architect their solutions accordingly. To maximize impact and adoption, the barrier-to-entry should be lowered by making development of new applications and the ingestion and exposure of smart objects as easy as possible. The IoTaaS conference aims to bring together researchers and practitioners interested in creating IoT-based value-added services from academia, industry, and SMEs. IoTaaS attendees will present novel ideas, exchange points of view, and foster collaborations. Papers, posters, and demos expressing the point of view of middleware and platform providers, smart object providers, application developers, and researchers are particularly welcome.