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mlight lee edited this page Feb 10, 2026 · 3 revisions

Welcome to the FAQ page!
Here you’ll find answers to common questions and troubleshooting tips about CAD-Viewer. If your question isn’t covered here, please open an issue or start a discussion.

📚 Table of Contents

💡 General Questions

❓ What is CAD-Viewer?

CAD-Viewer is an open-source DWG/DXF file viewer that runs directly in your browser — no installation required.
It provides features such as zoom, pan, layer control, entity selection, and layout switching, enabling users to explore CAD drawings easily.

❓ Who maintains this project?

This project is maintained by the mlightcad team and contributors from the open-source community.
You can find all contributors on the GitHub Contributors page.

❓ What license is used?

CAD-Viewer is released under the MIT License.
See the LICENSE file for full details.

🧾 File Support

❓ What file formats are supported?

Currently supported formats:

  • DWG: decided by libredwg. According to its document, it supports AutoCAD r1.2 through AutoCAD 2018.
  • DXF: decided by dxf-json which doesn't introduce the AutoCAD version supported yet.

❓ Are 3D DWG files supported?

CAD-Viewer currently focuses on 2D drawings. 3D viewing support is planned for future releases.

❓ Does it support DWG files created by AutoCAD vertical products such as AutoCAD Architecture, AutoCAD Mechanical, AutoCAD MEP, AutoCAD Map 3D, AutoCAD Plant 3D, AutoCAD Civil 3D, and Tianzheng Architecture (天正建筑)?

CAD-Viewer supports rendering the standard AutoCAD entities. If drawings created by those AutoCAD vertical products contain some custom entities, those custom entities will not be rendered. However, the standard entites in those drawing can be shown correctly.

❓ Are there any AutoCAD standard entity not supported yet?

  • Tables entities are not currently supported in DWG files because LibreDWG is used to read DWG files and it doesn't support table entity yet. If one table is created by line and polyline entities, definitely it is supported.
  • XRefs (External references) are not supported in both DWG and DXF and will not be displayed.

❓ Does it support layers, blocks, and layouts?

✅ Yes, CAD-Viewer supports:

  • Layer visibility control
  • Block references
  • Layout switching (Model / Paper space)

🧩 Troubleshooting

❓ Error message "Failed to get avaiable fonts" reported. What should I do?

Ensure opening VPN if you are in China. You can try to open font repository in browser. If you can't open this repository, it should be your network issue.

❓ The texts or characters display incorrectly.

If some of texts are shown incorrectly. It may occur due to missing fonts in DWG/DXF. CAD-Viewer use default fonts to display texts or characters in this case. There are two ways to handle it.

  • Create one pull request to font repository and add your fonts to this repository.
  • Host font repository in your own server. Please refer to this wiki page to learn hwo to deploy fonts on your own server.

if all of texts are not shown, please open 'Developer Tools' in browser and delete font cache database named 'mlightcad' in IndexedDB and refresh page again.

font cache

❓ What is the dependency relationship between @mlightcad/cad-simple-viewer and @mlightcad/data-model?

@mlightcad/cad-simple-viewer depends on @mlightcad/data-model for core CAD data structures and runtime behavior.

However, @mlightcad/cad-simple-viewer does NOT guarantee compatibility with all versions of @mlightcad/data-model.

If you upgrade @mlightcad/data-model independently (for example, using @mlightcad/data-model@1.7.0 together with @mlightcad/cad-simple-viewer@1.4.7), you may encounter runtime errors due to internal API or data structure changes.

✅ Recommended and Safe Usage

When using a specific version of @mlightcad/cad-simple-viewer, always:

  1. Check the revision history of its package.json
    👉 https://github.com/mlightcad/cad-viewer/blob/main/packages/cad-simple-viewer/package.json
  2. Use the exact same version of @mlightcad/data-model declared there.

This ensures the two packages remain compatible and avoids subtle runtime issues.

In short:
Treat @mlightcad/cad-simple-viewer and @mlightcad/data-model as a version-locked pair.

📜 License & Contribution

❓ Can I use CAD-Viewer in commercial projects?

Yes. CAD-Viewer is licensed under the MIT License, allowing both personal and commercial use.

❓ How should I acknowledge CAD-Viewer?

Please include a reference such as:

“Powered by CAD-Viewer”

📬 Contact

For questions or suggestions, you can reach us through:

🧭 Tip

If you discover a new common question, please help improve this FAQ by submitting a pull request!

Clone this wiki locally