As global environmental challenges increase, the need for integrated energy modelling to facilitate data-driven decision-making in energy policy and finance is critical. However, most existing integrated frameworks are limited in their applicability, granularity, and accessibility, risking the exclusion of developing countries from the global energy transition. Social dimensions are also often insufficiently addressed, and financial planning is not integrated, leaving gaps between technical analysis, social considerations, and actionable investment pathways. To address this, the article presents the Integrated Model for Policy, Actions and Collaborative Climate Transitions (IMPACCT), a new comprehensive framework that soft-links seven significant open-source tools—MAED; OnSSET; OSeMOSYS, including CLEWs and SIBs; FlexTool; PathCalc; MINFin; and FINPLAN—for the first time. IMPACCT estimates energy demands from the electrified and unelectrified populations and calibrates the least-cost capacity mix to meet demands while taking into account land availability, water use, carbon emissions, and social factors. The capacity mix is further refined to ensure power system flexibility, and the technical outputs are visualised in an engaging interface. Financial strategies at national and utility levels complete the framework, supporting the practical realisation of the technical plans. By outlining a new process with open-source, user-friendly interfaces, this paper increases accessibility and ease of use, supports capacity building in developing countries, and facilitates collaboration across institutions and disciplines. It delivers a significant leap in energy modelling, social inclusion, and financial planning, advancing a more integrated approach to sustainable development. Overall, IMPACCT enables more transparent and collaborative decision-making, accelerating financial mobilisation for a just energy transition.