Social Internet of Things (SIoT) enables IoT devices to discover the services offered by each other using a social network. The social network connects two devices if they have a common owner or both manufactured by the same company or they are situated at the same location etc. We advance the state of art in SIoT as we have developed a decentralized SIoT platform. Our solution eliminates the privacy and security issues with centralized SIoT platforms and scalability issues with blockchain- managed IoT platforms. Our main contributions are: We developed a decentralized SIoT platform where a de- vices neighbourhood is only known to the device. The lack of knowledge of SIoT network topology creates the problem of verifying the existence of paths between two devices. A malicious device may use false social neighbourhood information. Our SIoT platform deters such malicious devices. A primary objective of SIoT is to find a device providing a particular service. In a centralized SIoT platform, devices register the service they provide to a centralized entity. However, in a decentralized SIoT platform, the services provided by a device is only known to its neighbours. The challenge in a decentralized SIoT platform is to develop a search algorithm which do not reveal a social neighbourhood and which hides the identity information of the querying device and result of the search. Scalability is a problem for blockchain-managed IoT plat- form. We developed a blockchain offline channel-based solution for SIoT platform to address scalability issues.