In the era of digital communication, Online Social Networks (OSNs) have become a fundamental aspect of daily life, influencing information dissemination, community formation, and social influence. Assessing the strength of ties between users in OSNs is critical for applications such as targeted marketing, recommendation systems, and social influence analysis. Traditional methods for evaluating tie strength often rely on metrics that fail to capture the nuanced nature of human relationships. To address this, we propose a Fuzzy-based System for Assessment of Tie Strength (FSATS) in OSNs. Our system integrates multiple dimensions of tie strength, including Interaction Time (IT), Level of Intimacy (LoI), and Emotional Intensity (EI), leveraging fuzzy logic to handle the inherent uncertainty and complexity of social interactions. Simulation results demonstrate the effectiveness of FSATS, showing that increase of EI, IT, and LoI positively correlate with higher Tie Strength (TS).