An increasingly large amount of data is generated on the IoT. Widespread use of this data may help provide valuable insights and actionable triggers for new innovative services. To tap the potential of this increasing supply of data, a platform is needed. However in creating marketplaces for this data concerns regarding privacy and misuse of data are raised. This paper analyses several technologies that leverage the benefits of blockchain to attempt to mitigate these concerns. Mechanisms regarding data transfer, registration contracts and the responsibilities of gateway nodes are considered. The benefits and drawbacks of these technologies is discussed, as well as potential mitigations for these drawbacks. Finally the paper proposes a set of guidelines for future iterations of such platforms.