Galaxy Modeler is a schema design software for GraphQL that enables users to visually model GraphQL data by creating diagrams. The tool provides a graphical interface to define GraphQL schemas, specify object types, interfaces, enums, relationships between types, and other schema elements. Key capabilities include designing basic and complex GraphQL structures, auto-generating schema definition code, importing existing schemas, and producing documentation like PDF diagrams and HTML reports. With Galaxy Modeler, developers can visually model their GraphQL APIs instead of hand-coding schemas.