Reliable, high-quality risk assessment is the basis for an objective understanding of risk; priority for action 1 of the Sendai framework for disaster risk reduction 2015-2030. It is the foundation of decisions and actions that effectively build resilience. Earthquake risk continues to rise, yet reliable data, risk information, and assessment tools are out of reach or under-utilised in many areas of the world. The Global Earthquake Model (GEM Foundation) was created to bridge these critical gaps. Through authentic collaboration across public and private stakeholders, the GEM community supports risk management and awareness by developing and implementing open risk assessment tools, compiling and generating risk information. GEM influences risk reduction by promoting technology transfer and developing risk assessment capacity. All GEM risk assessment resources are made freely available through its web-based OpenQuake platform. As input to the Sendai framework, this paper provides an overview of GEM's achievements to date, lessons learnt - emphasizing effective modes of collaboration and capacity development -, and presents opportunities and challenges in going forward. This paper is from the Global Risk Forum Davos Planet@Risk Journal, which is no longer available.