The OSeMOSYS Global is a free modelling tool that lets users identify least-cost pathways to decarbonise the global energy system. It is open-source, uses open-data, and is publicly accessible at http://osemosys.global
The tool underpins much of the modelling and analysis done for projects across the GGI Ecosystem. It has now been peer reviewed and published in Scientific Data.
You can read the article here.