What is the VSJ file format?
A .vsj file is a scene-save file created by ViewSTL, a free online 3D model viewer by Omri Rips, and by its companion ViewStl JavaScript plugin. The name stands for ViewStl JSON, and the file is exactly that: a plain-text JSON document describing the state of a 3D scene.
Inside, a .vsj file records how the scene should look rather than what it contains. Stored values include canvas settings such as height and background color, the camera state (position, up vector and target), and an array of models. Each model entry keeps its source filename together with display attributes like color and transparency. The viewer writes this file through its save_scene function, which downloads the JSON with a default name of 1.vsj.
One detail matters most. A .vsj file does not hold any mesh geometry. It references external .stl or .obj files by name, so those files must still be available for the scene to render. When you want geometry and scene state travelling together, ViewSTL provides the related .vsb format, a ZIP archive that bundles a json.data.vsj entry with the STL models it needs.
Security & safety
RISK: LOWA .vsj file is plain-text JSON with no executable code, macros or scripts, so opening one cannot by itself harm your system. The only practical concern is that it references external STL/OBJ files by name; if those are missing the scene will not render fully. Editing the JSON by hand can break the syntax and stop ViewSTL from loading it, so keep a backup before making changes.
Format details
in a nutshellPrograms that open VSJ files
Windows4 apps
Notepad
Built-in Open the .vsj file to view its raw JSON text, though large single-line files may be hard to read. 
ViewSTL
Free Open viewstl.com, click the Open Model (folder) icon and select your .vsj file to restore the saved scene; keep the referenced STL/OBJ files in the same location so the geometry loads.
ViewStl JavaScript plugin
Freemium Embed the plugin in a web page and call its load_scene routine to read a .vsj file and rebuild the camera, canvas and model settings. 
Visual Studio Code
Free Open the .vsj file as text to read or hand-edit its JSON keys (canvas, camera, models); VS Code formats and validates the JSON. 
macOS2 apps
ViewSTL
Free Load the .vsj file through the Open Model icon in any browser to reopen the saved scene. 
Linux2 apps
ViewSTL
Free Use any modern browser to open viewstl.com and load the .vsj file to restore the scene.
ViewSTL
Free Drag and drop the .vsj file onto the viewer to rebuild the saved camera, background and model colors in the browser. Technical details
deep spec| Encoding | UTF-8 plain text (JSON) |
| Byte order | N/A (text format) |
| Container | JSON object |
| Compression | None (the compressed counterpart is the .vsb ZIP file) |
| Typical size | A few hundred bytes to a few kilobytes; the file stores scene settings only, not mesh geometry |
| Structure | A single JSON object holding the state of a ViewSTL scene: canvas settings (such as canvas height and background color), camera state (position, up vector and target), and an array of model entries. Each model entry references the source geometry by filename and stores display attributes such as color, transparency and visibility. |
| Integrity | None; integrity depends on valid JSON syntax |
| Platforms | Windows, macOS, Linux, Web browser |
| Notes | A .vsj file records how a scene should be displayed but does not embed the 3D mesh. It points at external .stl or .obj files by name, so those source files must be available for the scene to render. To bundle geometry and scene state together, ViewSTL uses the .vsb format, a ZIP archive that contains a json.data.vsj entry plus the referenced STL models. |
| Created By | The save_scene() method of the ViewSTL online viewer and the ViewStl JavaScript plugin |
| Default Filename | 1.vsj is the default name produced by save_scene() |
| Specification | www.viewstl.com |
VSJ conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about VSJ files.
Frequently asked questions
How do I open a VSJ file?
.vsj file. The viewer reads the JSON and restores the saved camera, background and model colors. Make sure the STL or OBJ files it references are available, because the geometry lives in those files, not in the .vsj.Does a VSJ file contain the 3D model?
.vsj file stores only scene settings such as canvas, camera and per-model display options. It references the actual mesh files by name. If you need geometry and scene state in one file, use the .vsb format instead.What is the difference between VSJ and VSB?
.vsj is the plain-text JSON scene description. .vsb is a ZIP archive that contains the same scene JSON (as json.data.vsj) plus the STL models, so a single .vsb file is self-contained and portable.Can I edit a VSJ file in a text editor?
Why won't my VSJ scene show any models?
.vsj only points at external model files by filename. If those STL or OBJ files are missing or in a different folder, the scene loads with its settings but no geometry. Restore the referenced files or use a .vsb bundle instead.What program creates VSJ files?
.vsj file (default name 1.vsj).
