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A tool to generate UML models from JSON schema documents.


To generate UML models:

  • Eclipse Modeling tools (it can be found here).

To visualize the generated UML models:

  • A UML 2.5 modeling environment in Eclipse such as Papyrus or UMLDesigner (we tested the tool with Papyrus).


  1. Open Eclipse IDE
  2. Click on Help / Install New Software...
  3. Click on Add... and fill in the form as indicated. The update site is
  1. Select JSONSchema to UML then click on Next.
  2. Follow the the rest of the steps (license, etc...) and reboot Eclipse.

Using the plugin

  1. Create a Project or use an existing project in your workspace.
  2. Import the JSON Schema documents in your Eclipse project.
  3. To generate a UML model from your documents you can right-click on a JSON file of your project or a folder containing your documents, and select the JSONSchema to UML/Generate Class diagram option.
  4. A UML model corresponding to the input definition will be generated in the folder src-gen of your project.

Visualizing the Class diagram using Papyrus

  1. Install Papyrus if you didn't do it yet (You can find the instructions here).
  2. Open the perspective Papyrus.
  3. Right-click on the generated UML model and select New -> Papyrus Model.
  4. Follow the steps in the wizard to initialize a Class diagram (keep everything as predefined except in the Initialization information step where you should check Class Diagram as the Representation kind).
  5. Drag-and-drop the UML elements from the Model Explrer into the editor.
  6. Align and arrange the layout as you prefer.
  7. Save.

The mapping in a nutshell

The generation process apply this (non exhaustive) list of mappings:

  • Each JSON Schema element is represented by a UML Class
  • Properties in JSON Schema elements represent the properties of a UML Class.
    • If the property is of primitive type it will become an attribute in the UML Class
    • If the property is of type enum, an Enumeration will be created and an attribute in the UML Class will be added
    • If the property is of type object or refers to other element (using $ref), an association is created in the UML Class. The type of the association corresponds to the UML Class element created from the object (or the referred object)
  • Hierarchies are created from allOf, oneOf, anyOf
  • The elements defined in definitions are considered as a library of JSON Schema elements and therefore they generate new UML Classes
  • The folder structure is used to created UML Packages containing the UML Classes coming from the JSON Schema files.