Gaze analysis has evolved into a mature technique with diverse applications enabling the investigation of various human activities and cognitive processes such as reading, visual attention, memory as well as real time gaze interaction. However, existing proprietary software or librairies often lacks the flexibility needed to incorporate emerging gaze metrics or real time processing, limiting researchers to predefined methodologies. To address these limitations, we introduce ArGaze, an open and flexible software library designed to provide a unified and modular approach to gaze analysis or gaze interaction. ArGaze facilitates real-time and/or post-processing analysis for both screen-based and head-mounted eye tracking systems. By offering a wide array of gaze metrics and supporting easy extension to incorporate additional metrics, ArGaze empowers researchers and practitioners to explore novel analytical approaches efficiently. This paper first reviews existing software solutions and their functionalities before delving into the design principles and features of the ArGaze library. Subsequently, three use cases demonstrate ArGaze’s efficacy in processing eye data from screen-based and head-mounted eye trackers, showcasing its versatility and applicability across different research and practical contexts.