Format Guide

glTF / GLB File Format (.gltf, .glb)

The web standard for 3D — compact PBR rendering, native browser support, and universal AR/VR compatibility.

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Valve with handwheel (STEP → GLB), rendered from the converted file — **STEP → GLB**Valve with handwheel: 8.7 MB STEP → 13.9 MB GLB at Standard quality, 171,790 triangles, 7.0 s (Ryzen 9 3900X).

Where this format fits

Your file

Solid CAD

STEP
IGES
BREP

Meshes

STL
OBJ
3MF
PLY
glTF
GLB
FBX
DAE
X3D
OFF
AMF

3D faces in drawings and scenes

3D CAD Converteropens, previews, converts

What you get

3D printing

Web, AR and games

glTF
GLB
FBX
DAE

Viewers and archives

VRML
X3D
OFF

CAD exchange

STEP
IGES
BREP

Solid CAD (STEP, IGES, BREP) can become a mesh or another solid format. A mesh converts to other meshes. Dashed formats (DXF, DWG, AMF, USD) can be read but not written. VRML reads .wrl, .vrml and gzipped .wrz files and writes .wrl.

What it will not do

Convert a 2D-only DWG or DXF drawing. It needs 3D faces.
Turn a mesh (STL, OBJ, 3MF) back into STEP, IGES or BREP.
Read native SolidWorks, Inventor or CATIA files. Export STEP or IGES from that program first.

Extension	.gltf (JSON + external assets), .glb (binary bundle)
Full name	GL Transmission Format
Standard	Khronos Group glTF 2.0
Geometry type	Triangle mesh
Open standard	Yes
Supports PBR materials	Yes — metallic/roughness workflow
Supports animations	Yes — skeletal and morph target
Supports assemblies	Yes — scene hierarchy

What is a glTF file?

glTF (GL Transmission Format) is an open standard developed by the Khronos Group. Introduced in 2015 and reaching version 2.0 in 2017, glTF is designed for efficient delivery of 3D scenes to web browsers and real-time applications. It stores mesh geometry, PBR (Physically Based Rendering) materials, textures, animations, and scene hierarchy in a JSON-based format. GLB is the binary container variant that packages the JSON and all binary data into a single .glb file. glTF has been called the “JPEG of 3D” — the format most widely supported by web renderers, AR/VR platforms, and e-commerce product viewers.

Common Uses of glTF/GLB Files

Web 3D & E-Commerce

glTF is the native format for Three.js, Babylon.js, and model-viewer. Shopify, Amazon, and Google use glTF/GLB for interactive 3D product visualization.

AR & VR Applications

Apple AR Quick Look (iOS), Google SceneViewer (Android), and WebXR all natively load GLB files. Product AR experiences on mobile use GLB almost exclusively.

Game Engines & Real-Time Rendering

Unreal Engine, Godot, and Babylon.js natively import glTF. It is the preferred format for real-time scenes due to its compact size and GPU-ready structure.

Smaller GLB files for the web

When you target the web or three.js, download size matters. 3D CAD Converter can compress glTF and GLB output with meshopt (the EXT_meshopt_compression extension), which three.js, Babylon.js and model-viewer read with their meshopt decoder.

One checkbox on glTF/GLB export. Measured on a valve assembly with 171,790 triangles: a 13.9 MB GLB came out at 2.3 MB.

The compressed file needs a viewer with meshopt support. Leave the box unticked for tools that cannot read it.

Batch hundreds of CAD parts into compressed, web-ready GLB offline.

Compression is a desktop option: tick the mesh compression checkbox in the glTF options. The app labels it Draco; the file it writes uses meshopt compression. How to reduce glTF file size

How to convert to glTF / GLB

Turning a CAD model or mesh into a web-ready glTF or GLB file takes three steps in 3D CAD Converter.

Load your model

Drag a STEP, OBJ, FBX, STL or IGES file into the app, or drop a whole folder to convert many parts at once.

Choose glTF or GLB

Pick glTF for a JSON file with external assets, or GLB for a single self-contained binary. Set the mesh quality and, if you target the web, tick mesh compression in the glTF options.

Convert

Click Convert and the app writes the glTF or GLB file. The conversion runs offline, so your models never leave your machine.

Prefer the command line? The bundled CLI converts and batches glTF/GLB too:

Convert a STEP part to GLB
cadconvert convert part.step -o part.glb

Convert an OBJ mesh to GLB
cadconvert convert model.obj -o model.glb

Batch a whole folder (recursively) to glTF
cadconvert batch ./in -o ./out -f gltf -r

Add --units to set the scale. For mesh density, use --quality on STEP and IGES sources and --decimate on mesh sources such as OBJ or FBX. The CLI has no compression flag: to compress GLB output, use the glTF options in the desktop app.

glTF — the JPEG of 3D

glTF is often called the JPEG of 3D: it is the format browsers, AR viewers and real-time engines load fastest. If your model is destined for a website, an e-commerce product viewer, a three.js or Babylon.js scene, or an iOS or Android AR experience, glTF or GLB is almost always the right target. It carries PBR materials, textures, animations and a full scene hierarchy in a compact, GPU-friendly package.

Coming from a different mesh format? See how glTF compares to OBJ, FBX. Reduce glTF file size for the web

Common glTF issues and how to avoid them

Missing textures

A .gltf file can reference external image and .bin files. If those files are not shipped alongside it, the model loads untextured. Export to GLB instead — it bundles geometry, materials and textures into one file that is safe to move and share.

GLB vs glTF confusion

GLB and glTF hold the same data. .gltf is JSON plus separate asset files; .glb packs everything into one binary. Use GLB for the web, AR and sharing; use .gltf when you want to inspect the JSON or swap textures. 3D CAD Converter exports either.

Files too large for the web

Detailed CAD geometry can produce heavy GLB files that load slowly in a browser. Start with a coarser quality preset: the same valve assembly is 13.9 MB at Standard and 3.9 MB at Draft. Then tick mesh compression in the glTF options, which took the 13.9 MB file to 2.3 MB. See the file-size guide

Software Support

Blender, Sketchfab, Three.js, Babylon.js, Unreal Engine, Godot, Unity (via plugin), iOS AR Quick Look, Android SceneViewer, and all modern web 3D renderers.

Convert This Format

Commonly converted from STEP or OBJ for web visualization and e-commerce, to GLB for a single self-contained file, or to OBJ for legacy renderers.

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glTF / GLB — Frequently asked questions

What is a .glb file?

A .glb file is the binary form of glTF. It bundles the JSON scene, mesh geometry, PBR materials, textures and animations into a single self-contained file, which makes it the easiest 3D format to share and to load on the web, in AR and in game engines. A .gltf file holds the same data but may reference external .bin and image files.

What is the difference between glTF and GLB?

They are the same Khronos format in two packagings. A .gltf file is JSON that can point to external geometry and texture files, so it ships as several files; a .glb file packs everything into one binary. Use GLB for the web, AR and easy sharing; use .gltf to inspect the JSON or swap textures separately. 3D CAD Converter exports both.

How do I convert a STEP or OBJ file to GLB?

Open the STEP or OBJ file in 3D CAD Converter, choose glTF/GLB as the output, and convert. Drop a folder to batch many parts. From the command line run cadconvert convert part.step -o part.glb or cadconvert convert model.obj -o model.glb. To shrink the result, tick mesh compression in the glTF options of the desktop app.

Can I open a glTF or GLB file without Blender?

Yes. GLB files open in many free viewers, including the Windows 3D Viewer, the Khronos glTF Sample Viewer, the Babylon.js Sandbox and Google model-viewer in any browser. 3D CAD Converter previews glTF/GLB and converts it to OBJ, STL, FBX and more. You do not need Blender to view, share or convert a glTF file.