The digital platform market is one of the fastest growing markets. Amazon, Google, Apple, and Facebook are perhaps one of the most successful companies in IT space right now due to their digital platform offerings. Most of the enterprises are leveraging digital platforms to maximize operational excellence, enhance the customer experience, develop new business opportunities, and monetize internal resources. According to IDC, the Industrial Internet of Things (or Industry 4.0 -The fourth industrial revolution) will shape the evolution in the Industrial IoT platform vendor landscape. This book aims to provide an overview of open source technologies to build a digital platform for the Industrial Internet. It begins with a broad overview of Industrial Internet concepts for those, who want to understand what IIoT is. After that, the follow-on chapter dives deeper into the digital platform and its use case scenarios for Industrial Internet. Finally, we present open source tools and technologies, which are relevant for building a digital platform for the Industrial Internet.