We present a remote assistance system that enables a remotely located expert to provide guidance using hand gestures to a customer who performs a physical task in a different location. The system is built on top of a web-based real-time media communication framework which allows the customer to use a commodity smartphone to send a live video feed to the expert, from which the expert can see the view of the customer’s workspace and can show his/her hand gestures over the video in real-time. The expert’s hand gesture is captured with a hand tracking device and visualized with a rigged 3D hand model on the live video feed. The system can be accessed via a web browser, and it does not require any app software to be installed on the customer’s device. Our system supports various types of devices including smartphone, tablet, desktop PC, and smart glass. To improve the collaboration experience, the system provides a novel gravity-aware hand visualization technique.