OmniGraffle is for creating precise graphics like website wireframes, an electrical system designs, or mapping out software class.
LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
Online diagramming application
Simplify and communicate complex information using data-linked diagrams.
PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.
Gliffy is a powerful HTML5 online diagram maker. Create a flow chart, network diagram, UML diagram, organizational chart or wireframe with ease.
Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
Instead of starting with a blank screen, SmartDraw gives you the exact template you need.
The prototyping and specification software used by 87% of the Fortune 100. Beyond mockups, design interactive prototypes for business solutions, websites, and applications.
Professional digital design for Mac.