UML File

What are UML files and how to open them

Are you having problems opening an UML file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your UML files.

What is an UML file?

An .UML file is a StarUML Model file.

StarUML Model files (extension .uml) are project files saved by StarUML version 1 (not the newer JSON-based versions). These files store all models, views and diagrams created in a UML project. The structure includes data for UML profiles, referenced unit files, the model elements themselves (such as classes, packages, subsystems), and their visual layout (diagrams, views). These files are used when building, editing and saving complete UML software design projects with StarUML 1.

A typical StarUML Model .uml file is an XML document written in UTF-8 encoding following XML version 1.0. It begins with an XML declaration like <?xml version="1.0" encoding="UTF-8"?> and includes sections that describe owned elements, diagrams, views, packages, namespaces, and the relationships among model elements. The file may be split into multiple units (.UML or .UNT) for collaboration, and can reference other UML profiles.

For internal identification, these files start with the ASCII-bytes for "<?xml version="1.0" encoding="UTF-8"?>" at offset zero. They contain keywords such as UMLPROJECT, UMLMODEL, OWNEDDIAGRAMS, OWNEDELEMENTS, UMLCLASSDIAGRAMVIEW, and strings like WWW.STARUML.COM and DOCUMENTELEMENT.

How to open UML files

We have identified one UML opener that is compatible with this specific type of UML file.

Programs that open StarUML Model files

Last updated: August 13, 2026

Various apps that use files with this extension

These apps are known to open certain types of UML files. Remember, different programs may use UML files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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