Free tool
Online OBJ viewer
Open an OBJ in seconds. Check its size, triangles and shape before you print or convert it.
Runs in your browser. Nothing is uploaded.
How to use it
1Open the OBJ
Drop the .obj file or try the sample. The .mtl and texture images are not needed to see the shape. Nothing is uploaded.
2Turn it upright
OBJ files have no fixed up axis. If the model lies on its back, switch Z axis is up off or on.
3Look around
Drag to orbit, scroll or pinch to zoom, right-drag to pan. Toggle wireframe to see how dense the mesh is.
4Read the numbers
Size on X, Y and Z, triangle count, volume and surface area, in millimetres or inches. Save a PNG of the view if you need one.
To view an OBJ file online, drop it on the viewer above. The model opens in 3D in your browser, with its size in millimetres, its triangle count and its volume, and nothing is uploaded. STL, 3MF, PLY and GLB files open the same way.
Opening OBJ files on Windows and Mac
Windows. Microsoft's own viewers are gone from the Store. Microsoft removed 3D Viewer from the Microsoft Store on July 1, 2026, after Paint 3D (November 4, 2024) and 3D Builder (July 2024). 3D Viewer was preinstalled on some Windows 10 PCs but never on Windows 11. Existing installs still work. For viewing 3D content, Microsoft suggests the Babylon.js Sandbox, which opens .obj, .glb, .stl and .ply files in a browser.
Mac. Preview handles it. Apple's list of 3D formats Preview supports for macOS 27 includes Wavefront OBJ, STL, PLY, glTF and GLB, and USDZ. Choose File > Open in Preview, or use the viewer here on any older Mac.
What an OBJ file is, and why it comes with an .mtl
OBJ is a plain-text format. The OBJ specification defines lines starting with v for vertex positions and f for faces, which need at least three corners and can have more. Optional o and g lines name objects and groups.
Colour lives elsewhere. An OBJ names a material library with mtllib, usually a .mtl file, and switches materials with usemtl; the library can point to image files for textures. That is why OBJ downloads often come as a folder: .obj, .mtl and a few images. If the .mtl is missing, the shape is still complete. This viewer shows the shape in a single colour you choose.
| File | Holds | Needed to see the shape |
|---|---|---|
| .obj | Vertices, faces, objects, groups | Yes |
| .mtl | Colours and material settings | No |
| .png or .jpg | Texture images | No |
When an OBJ looks wrong
- Lying on its back. The format does not say which axis is up. Toggle Z axis is up: it starts off for OBJ, on for STL and 3MF.
- Wrong size. OBJ has no units. The measurements assume millimetres, so a model saved in metres shows as a tiny fraction of a millimetre. The Blender manual itself notes that OBJ files often vary greatly in scale.
- Faceted or very heavy. Wireframe view shows how many triangles the mesh uses, and the count is in the panel.
Convert it after viewing
To print the model, use the OBJ to STL converter: it turns the model upright, fixes the units and checks it for holes. For 3MF, GLB or PLY, use the STL file converter, and to go the other way, the STL to OBJ converter. For STL files the STL viewer has the same controls.
Questions
How do I open an OBJ file without installing software?
Drop it on the viewer on this page. It opens in your browser on Windows, Mac, Linux or a phone, and the file is read on your device, not uploaded.
Can Windows 11 open OBJ files?
Windows 11 never came with 3D Viewer, and Microsoft removed that app from the Microsoft Store on July 1, 2026. Existing installs keep working. For viewing 3D content, Microsoft now suggests the Babylon.js Sandbox in a browser, or use the viewer on this page.
Can a Mac open OBJ files?
Yes. Apple's Preview user guide for macOS 27 lists Wavefront OBJ among the 3D formats Preview opens with File > Open, along with STL, PLY, glTF and USDZ.
What is the .mtl file that comes with an OBJ?
The material library. The OBJ refers to it by name and uses it for colours and the image files used as textures. Without it you still see the full shape, just without colours.
Why does my OBJ look sideways or the wrong size?
OBJ stores plain numbers with no units and no rule about which axis is up. Switch Z axis is up if it lies down. Sizes are shown as millimetres; a model saved in metres reads 1,000 times too small.
Can I convert the OBJ after viewing it?
Yes. The OBJ to STL converter turns it into a printable STL with the size and orientation fixed, and the STL file converter also writes 3MF, GLB and PLY.
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