The EMBL-EBI Complex Portal is an encyclopaedic resource providing high quality, manually curated, functional biomolecular complexes. Those complexes consist mainly of proteins but they may also contain small molecules, nucleic acids and subcomplexes. The Molecular Complex Navigator facilitates the visualisation of large sets of related complexes in a context-specific manner. The Complex Navigator is implemented as a matrix, with the complexes represented as rows, and the interactors as columns. Users can access detailed information on both complexes and interactors via clickable links on their names. Selecting a complex link directs users to its detailed Complex Portal page, while selecting an interactor link provides access to a page with information on the interactor, which could be from UniProt, ChEBI or Complex Portal page depending on the interactor type. The matrix also features an expandable menu to view subcomplexes" interactors, and each matrix cell displays the stoichiometry of the complex interactors. The Molecular Complex Navigator is designed to simplify and enhance the visualisation of multiple closely related complexes and their interactors.