draw.io - Online diagramming application
Procore - Procore is the world's most widely used construction project management software. Easy to use, mobile platform with unlimited user licenses.
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.
Corecon - Corecon offers integrated estimating, project management, and job costing for small to medium-sized construction companies.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
BuilderTREND - Buildertrend is the #1 construction management software and construction app for home builders, remodelers, specialty contractors and commercial construction.