DataCAD - DataCAD is a computer-aided design and drafting software for 2D and 3D architectural design and drafting
LucidChart - 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.
AutoCAD Arch - Design and document more efficiently with the AutoCAD Architecture toolset, created specifically for architects.
draw.io - Online diagramming application
AutoCAD Plant 3D - AutoCAD Plant 3D is a BIM software that lets you create, modify, and manage schematic piping and instrumentation diagrams.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.