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.
Oak Engage - Oak Engage is a digital workplace for enterprises that need to communicate with their workforce. Connect your teams. Engage your people.
draw.io - Online diagramming application
Nextcloud Hub - On-premises, enterprise collaboration solution for documents, emails, calendars and more.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Zendo - Zendo allows you to sell productized, subscription and custom services. Collaborate and collect payments. Create quotes and invoices. Eliminate multiple tools and enjoy the simplicity.