MySQL Workbench - MySQL Workbench is a unified visual tool for database architects, developers, and DBAs.
draw.io - Online diagramming application
DBeaver - DBeaver - Universal Database Manager and SQL Client.
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.
DB Designer - fabFORCE.net Database Tools
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.