This article originally was published on World Resources Institute. In the aftermath of the 6.5 magnitude earthquake in Aceh, Indonesia, in 2016, disaster managers were able to able to identify which communities were at greatest risk due to rapid access to data. They used the open source InaSAFE platform to access real-time hazard data and modeled population data mapped down to the village level. This was made possible by the collaborative use of "open" data — data that is free to use, open license and in machine-readable formats — between scientists, local and national governments and communities. By using open data, disaster managers were able to develop 20 disaster contingency plans with communities.