Astah Community is a free software design tool which supports the latest UML diagrams.

Diagram Designer is a vector graphics editor that allows you to create UML class diagrams, illustrations, flowcharts and slide shows.

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

Grafio is a fun and capable diagraming app for iOS with plenty of features at a fraction of the cost of others.

Microsoft Visio (formerly Microsoft Office Visio) is a diagramming and vector graphics application and is part of the Microsoft Office family.

Nevron Draw is a software for creating flowcharts and diagrams.

Dia is free and open source drawing software.

draw.io is free online diagram software for making flowcharts, process diagrams, etc

Enterprise Architect is a visual modeling and design tool based on the OMG UML.

Lucidchart is a web-based application to draw diagrams.

Modelio is an Open Source UML tool.

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