PlantUML

PlantUML is a component that allows to quickly write UML diagrams. Diagrams are defined using a simple and intuitive language. (see PlantUML Language Reference Guide).

Gitlab WIKI supports integration with the PlantUML server. This integration allows UML diagram to be directly included in Gitlab wiki pages, not as images, but rather as code snippets (PlantUML supports defining UML diagrams in terms of a domain specific language -DSL).

Some additional material:

• Each Gitlab repository contains a WIKI that in turn is another git repository. This means that WIKI pages can be cloned and authored locally and off-line.
• Gitlab support the popular formats Markdown, AsciiDoc
• UML diagrams are defined in terms of a domain specific language defined in PlantUML
• Plantuml diagrams can be authored and rendered locally using the typical tools such as Visual Code, InteliJ etc.