ActiveModeler Avantage is a business process modeling platform that provides BPMN 1.1 compliant process diagram editing, multiple projects, and a .NET process modeling framework. It has key features like organizational structure mapping, model categories, process navigation, plugin extensibility, project orientation, BPMN diagramming, workflow automation, content management, SOX compliance, version history, and web exporting. The platform allows adding features through plugins and organizing work into projects with BPMN diagramming storing data in XML files.