Online Social Networks (OSNs) play a vital role in daily interactions, influencing information flow and community building. Understanding the strength of ties between users in OSNs is essential for various applications such as personalized marketing and recommendation systems. Traditional methods for evaluating tie strength often overlook the complexity and subtlety of human relationships. This paper introduces a Fuzzy-based System for Assessment of Tie Strength (FSATS) in OSNs, which integrates Interaction Time (IT), Level of Intimacy (LoI), Emotional Intensity (EI), and Reciprocity (Rc) parameters to evaluate the Tie Strength (TS). Simulation results demonstrate a positive correlation between higher values of IT, LoI, EI, and Rc and increased TS, validating the effectiveness of the proposed system. This research highlights the potential of FSATS to advance the understanding of social dynamics in OSNs.