Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.
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.
Microsoft Teams - Microsoft Teams provides the enterprise-level security, compliance and management features you expect from Office 365, including broad support for compliance standards, and eDiscovery and legal hold for channels, chats, and files.
draw.io - Online diagramming application
Creativity 365 - Cross-device content creation suite
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.