This paper designs and implements a mobile crowd-sourced guiding system, called EasyFind, using smartphones to guide indoor people and find lost items through Internet of Things (IoT) technologies. In normal time, the EasyFind system can provide the fastest guiding path with the shortest moving time to a destination place based on the density of indoor people in each area. In addition, in emergency time, the EasyFind system can evacuate all people in the shortest total escaping time through modeling spatial and temporal mobilities of indoor people. Furthermore, the EasyFind system can cooperatively find lost items equipped with mobile iBeacon nodes through participatory sensing networks formed by mobile users with smartphones in places with static iBeacon nodes. To precisely localize the lost item, six item localization cases are addressed to reduce the positioning errors with different numbers of smartphones detecting the lost item and different numbers of fixed iBeacon nodes nearby these item-detecting smartphones. An Android-based prototype with static and mobile iBeacon nodes is implemented to verify the feasibility and correctness of our EasyFind system.