Free online MDJ to SVG converter

What the MDJ format is

MDJ is the JSON-based project format used by StarUML. It stores the UML model, diagram definitions, relationships, element properties, and project metadata; a single file can contain multiple diagrams such as activity, state, class, sequence, component, and use-case diagrams.

You normally encounter an MDJ file when a StarUML user sends a project for collaborative editing, backup, or archival. It is a structured model file, not a standalone image, so ordinary image converters cannot reliably render it without interpreting StarUML's diagram data.

What the SVG format is

SVG is an XML-based vector graphics format. Lines, shapes, and text remain defined as scalable objects, so an exported diagram stays sharp when printed, enlarged, or embedded in an HTML page.

SVG is suitable for web publishing, documentation, presentations, illustration editors, and repositories that need a diagram preview. Unlike MDJ, it contains the visual drawing rather than the editable StarUML model, UML relationships, or project structure.

How to actually convert MDJ to SVG

Using StarUML

1. Install and open StarUML, then choose File → Open and select the .mdj project.
2. In the Model Explorer, open the diagram you want to export. MDJ projects can contain several diagrams, and export normally applies to the currently selected diagram.
3. Choose File → Export Diagram or the equivalent diagram-export command in your StarUML version.
4. Select SVG as the output format, choose a destination and filename such as activity-diagram.svg, then confirm the export.
5. Open the SVG in a browser or vector editor to check text, connectors, page bounds, and arrowheads before distributing it.

If StarUML offers only a general export dialog, select the current diagram and choose SVG rather than exporting the entire project. Repeat the operation for each diagram that needs a separate SVG file.

Using the built-in online converter

You can convert the file for free on 101convert.com without installing software: upload the MDJ file, select SVG as the target format, start the conversion, and download the resulting file. Use StarUML instead when the project contains sensitive model data or when you need to control the rendering of individual diagrams.

Quality and compatibility limits

• The result is a visual export, not a recoverable StarUML project. Editing the SVG does not update the original UML model.
• Export one diagram at a time unless the converter specifically supports batch extraction from multi-diagram MDJ projects.
• Fonts installed on the source computer may not exist on the viewing computer. For predictable appearance, open the SVG in a vector editor and convert text to outlines only after keeping an editable copy with live text.
• Custom StarUML extensions, external images, clipped objects, or unsupported diagram elements may render differently or be omitted. Inspect the exported SVG rather than assuming every project element transferred correctly.