A Foot Insole system is designed and developed, for real time monitoring of ground reaction forces and gait parameters while performing various activities. In this paper, the various activities includes walking, stair ascend and stair descend. Force Sensing Resistors are integrated in the foot insole to capture the required set of data and post-processed. Accelerometer sensors readings are also collected at each step, to analyze the reaction forces at the knee and the ankle joint. The data was captured with 5 healthy subjects, performing the aforementioned activities. The average peak reactive force at the foot and the joints are compared. The reactive forces are higher during stair descend when compared with the reactive forces generated during stair ascend and walking. The paper also highlights the possible application of the developed device in medical and sports related fields.