STL → GLB / glTF Converter

Both are versions of the same format (glTF 2.0, the “JPEG of 3D”). GLB is a single binary file — geometry, textures, and metadata packed together. glTF is a JSON file that may reference external resources (textures, binary data). For sharing or embedding a single model, GLB is almost always the right choice. glTF is useful if you need to edit the file manually or inspect its structure in a text editor.

Pick GLB unless you have a specific reason not to. It’s a single self-contained file, smaller, and accepted by all modern 3D viewers and engines. Choose glTF only if you need a human-readable JSON file (e.g. for debugging, scripting, or pipelines that expect text-based formats).

Yes. The exported GLB conforms to glTF 2.0 and works in <model-viewer>, three.js, Babylon.js, Sketchfab, Unity, Unreal, Blender, and any other tool that accepts glTF. Just drop the file into your scene or set it as the src attribute.

For Android and WebXR — yes, GLB works directly. For iOS AR Quick Look you need USDZ, which Apple’s free Reality Converter can generate from a GLB file in seconds. So the typical workflow is: STL → GLB (here) → USDZ (in Reality Converter, if needed for iOS).

GLB uses indexed geometry — each vertex is stored once and referenced by the triangles that share it. STL stores each triangle’s three vertices independently, even when they’re identical. For typical engineering models this redundancy makes STL 2–5× larger. The geometry itself is identical.

Different 3D software uses different conventions for which axis is “up”. Web 3D formats (GLB, glTF) and three.js use Y-up. CAD and BIM tools like Revit, AutoCAD, FreeCAD, and SolidWorks use Z-up. STL files exported from these tools carry Z-up coordinates, which appear rotated when loaded into a Y-up viewer. Use the “Source up axis” toggle in the file info panel to switch — your model will display upright in the preview, and the exported file will be saved in standard Y-up orientation.

Yes. The conversion is lossless — every triangle from the STL appears in the GLB with the exact same vertex positions. Vertex normals are computed if the STL didn’t include them. No simplification, no smoothing, no decimation.

Standard STL files don’t store color — only geometry. The “colored STL” variant from some 3D printer slicers stores per-triangle color in a non-standard way that’s inconsistently supported. This converter focuses on geometry only. If you need color/material, start from an OBJ or 3MF file instead.