Achieving global climate goals requires a transformative shift in decision-making, investments, and policy adjustments. Energy system models play a crucial role in this process, enabling informed decisions for optimizing investments, forecasting trends, and shaping regulations. This policy brief highlights the importance of open-source energy modeling as a key driver of the energy transition. Open models offer transparency, flexibility, and cost-effectiveness, ensuring a collaborative and data-driven approach to tackling climate challenges. By fostering innovation and inclusivity, open energy modeling provides robust tools for policymakers, regulators, and investors to navigate the complexities of modern energy systems. The document outlines the benefits of open-source models, their potential applications, and the steps needed to integrate them effectively into global energy planning.