Many methods and tools have been developed to help original equipment manufacturers to shift towards circular business models (CBM), however, a gap is observed for decision making support that allows to test different functions of a CBM (e.g., product design and financial and environmental assessment) and their prompt exchange of relevant information. To overcome this, a design platform concept is proposed, aiming to transcend existing frameworks' limitations and link engineering and managerial aspects. Focused on delivering Product-as-a-Service for electrical and electronic equipment, the platform concept aims to reduce global electronic waste and extend product lifespans. The framework proposed involves a holistic approach encompassing product architecture, service ecosystems, and new digital technologies. Emphasis is placed on a hierarchical product architecture structure, a well-developed service ecosystem involving various stakeholders, and the integration of digital twins, data management, and artificial intelligence. Specific performance and circularity indicators within the design platform concept will address the challenges related to circularity, business model development, and sustainability. These indicators encompass decision tools focusing on both product and business model design and operation with the help of different ease of X decision tools (repair, refurbish, remanufacture, reuse, and recycle). Additionally, sustainability validation tools, including life cycle assessment, critical raw material assessment, life cycle cost analysis, and social life cycle assessment, will support informed decision-making within the design platform concept.