yEd is a free general-purpose diagramming program with a multi-document interface.

OmniGraffle is a diagramming and digital illustration application for macOS and iOS.

Creately is a collaborative diagramming and design software used by teams around the world to communicate more effectively.

Edraw Max is comprehensive mind mapping and planning tool network diagrams, floor plans, workflow diagrams, business charts, and engineering diagrams.

Calligra Flow (Kivio) is free diagramming software that is a part of Calligra Suite, an integrated graphic art and office suite by KDE.

Storyboard That is a free online storyboard creator.

Nevron Draw is a software for creating flowcharts and diagrams.

LibreOffice is a full-featured office productivity suite that provides a near drop-in replacement for Microsoft Office.

Apache OpenOffice Draw. Makes drawing business processes and diagrams a snap! Draw - from a quick sketch to a complex plan, Draw gives you the tools to commun…

PlantUML is an open-source tool allowing users to create UML diagrams from a plain text language.

UMLet is an open-source Java-based UML tool designed for teaching the Unified Modeling Language and for quickly creating UML diagrams.

Lovely Charts is an online diagramming application that allows you to create professional looking diagrams, such as flowcharts, sitemaps, organisation charts,…

ProcessOn is an easy-to-use, free and powerful online diagram designer which support to share and real-time collaboration.

Aqua Data Studio is a tool for database modeling.