Bluetooth Low Energy (BLE) beacons are widely adopted in a vast range of industries involving the Internet of things (IoT). BLE is primarily used for indoor location estimation. It is often utilized to provide contextual information with low energy consumption and low-cost mobile beacons. BLE beacons are currently deployed in superstores, stadiums, and hospitals to leverage proximity marketing, inventory management, utility management, as well as enhancing usability. In this dissertation, I propose and explore a novel system, named ‘Users-as-Beacons’ (U-a-B) built upon BLE technology, where BLE-enabled smartphones become live beacons.In my research, I explore the possibility of developing U-a-B systems through multiple user studies. In these studies, I investigate the following research questions. (i) What are the potential application areas and appropriate contexts of U-a-B? (ii) What are the users’ preferences for the disclosure of personal information in U-a-B? and (iii) What are the general perceptions and preferences, particularly around privacy, of users in U-a-B?From the exploratory studies, I classified the potential application areas including localized advertising platform for shopping areas, instant review platform for shopping areas, a crowdsourced localized platform for reviewing places, and community-based social networks. I also identified several design challenges to develop such a system, such as the trustworthiness of the system, relevance of the contents, timeliness of the content delivery, and the desired form of interactions among users. Subsequently, I developed a fully working real-life prototype and deployed it in a festival. Based on all these results, I describe a set of privacy-preserving design guidelines to implement a scalable, usable, and privacy-preserving Users-as-Beacons platform.