Montreal Open Clusters and Associations (MOCA) is an astronomy database and web tool for exploring stellar associations, open clusters, and their members. It brings together datasets from MOCA tables and presents the latest available information in convenient reports about individual stars, associations, and publications. Users can search by a star’s name, an association’s full or recognized abbreviated name, or a publication identifier.

The search interface also supports wildcard characters, coordinate-based searches with an optional radius, and queries using a unique MOCA object identifier. These features help researchers and other users locate and review relevant astronomical data without needing to search tables manually. MOCA is connected to the work of Jonathan Gagné and provides links to the Planétarium de Montréal, the Trottier Institute for Research on Exoplanets, the Unified Cluster Catalogue, and the BANYAN Σ web tool.

The site also offers information about the database, its schema, and ways to query and visualize its data, with additional guidance for matching custom star-name lists through the mocapy Python package