Envoy - Visitor registration that's changing how guests are greeted in companies around the world.
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.
Envoy Passport - Visitor sign-in just got even easier
draw.io - Online diagramming application
Teamgo - Create a safer workplace for your visitors and employees. Teamgo visitor management captures sign-ins, prints badges, sends arrival notifications and emergency alerts.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.