AI and Blockchain are two disruptive technologies that have the potential to change business models and impact the society. Their integration can lead to Decentralized AI, which enables analysis, decisions and self-learning on trusted and shared data stored on the Blockchain. Autonomous agents in a multi agent environment can collaborate, act and take decisions. Decentralized AI can help improve system performance by processing relevant data, as well as perform parallel processing across nodes based on different objectives. This paper reviews concepts of Blockchain, AI, power of combining these two technologies, and different platforms providing these capabilities.