Madaster is an online registry which aims to enable and promote circularity in the construction industry and eliminate waste.

Data are recorded on all components used in a real estate or infrastructure project, such as buildings and bridges. This provides information on how an object can be dismantled and whether the resulting materials can be reused, along with details on embodied carbon and toxicity. 

The site includes the Madaster Platform, where material passports can be created. The platform adds details on circularity, environmental impact and residual value. Users can search for specific materials within a set area and ensure that their project complies with regulations. Policymakers and anyone looking for data on the built environment can find relevant data.