Data Catalog is a MongoDB database containing multiple interlinked collections. The schema and linkage rules for those collections is described using JSON schema and managed by code in the python-datcatalog package. Data is loaded into and managed within the database interactively using management tools in the python-datcatalog source repository and automatically by Reactors that build on the python-datcatalog package. The Data Catalog is also populated by ETL pipelines via interfaces to the Data Catalog.