As Industry 4.0 revolutionizes manufacturing, the integration of Internet of Things (IoT) technologies with Enterprise Resource Planning (ERP) systems becomes essential for optimizing production processes and enhancing opérational efficiency. This paper conducts a comparative study of two prominent open source ERP systems—Odoo [10] and ERPNext [11] —evaluating their suitability for smart manufacturing environments. Leveraging the lightweight Message Queuing Telemetry Transport (MQTT) protocol, the study examine each system's performance in term of scalability, customization, and integration capabilities. Through détailled analysis and real-world case studies, we highlight the strengths and weaknesses of each ERP solution, offering practical recommendations for organizations aiming to adopt open source ERP systems in the context of Industry 4.0. The findings underscores the potential of open source ERP systems to facilitate seamless data flow, real-time monitoring, and automated decision-making, thereby advancing the objectives of smart manufacturing.