This is the most common environment for .uml files. You can use the Eclipse UML2 plugin to open and edit these models.

Because .uml files are typically XML-based files generated by specific modeling tools, you can open and view this guide by using one of the following software applications: Tools to Open and View .uml Files

Showing how objects interact in a specific time sequence.

Describing how users (actors) interact with the system.

If this file follows standard UML conventions, it likely contains one of these core diagram types:

If you prefer code-based viewing, you can sometimes import the raw data into PlantUML to generate a visual diagram. What to Expect Inside

These are robust desktop applications designed for creating and reading standardized UML files.