Apache OpenOffice

Apache OpenOffice is a free, open productivity suite with tools to create diagrams, charts, and illustrations. It enables brainstorming, basic flowcharting, and data import/export. While not as feature-rich in diagramming as dedicated tools, it supports document storage, drag-and-drop editing, and templates. With offline capabilities, it’s suitable for simple workflows and collaboration through file sharing. OpenOffice helps individuals and businesses produce various diagrams and documents at no cost.