Open3D Blog
Practical guides to 3D file formats — what they are, how to open them, how to convert them, and which one to use for your project. Written for anyone who handles 3D files: 3D printing hobbyists, modelers, engineers, and anyone who got sent a file and needs to figure out what to do with it.
Format primers — what each file type is
- What is an STL file? A complete guide
The original 3D printing format — what it stores, what it doesn't, and why it became the universal standard.
- What is a GLB file? Understanding glTF Binary
The web-and-AR-friendly 3D format. PBR materials, animations, Draco compression, and where to use it.
- What is a STEP file? The universal CAD interchange format
How mechanical engineers move parts between Fusion 360, SolidWorks, Inventor and beyond.
- What is a 3MF file? The modern replacement for STL
Multi-material, colour, build settings, and slicer support — what 3MF adds and where it's heading.
- What is an OBJ file? Wavefront's open mesh format
The 3D modeling workhorse — geometry, materials, when it shines and where it falls short.
Format comparisons — which to use when
- STL vs OBJ — which 3D format should you use?
Triangles vs polygons, single-file vs material library, and when each one is the right pick.
- STL vs 3MF — the case for moving on from STL
What 3MF fixes about STL, and when STL is still the safer choice.
- GLB vs glTF — picking the right one for web and AR
Same format, different packaging. When to pick each container.
- STEP vs IGES — choosing a CAD interchange format
Why STEP replaced IGES, and where IGES still makes sense.
- STL vs STEP — mesh vs parametric CAD explained
The fundamental difference and how it changes what you can do with each.
How-to guides
- How to open an STL file on iPhone
Three working ways — browser, app, or convert to USDZ for Quick Look.
- How to open an STL file on Android
Browser, native app, and AR via Scene Viewer.
- How to view a STEP file without AutoCAD or Fusion 360
Free options ranked by what you can do after opening.
- How to view a GLB or glTF file in your browser
Drag-and-drop viewers, model-viewer, and three.js.
- How to convert STL to GLB
Blender, glTF-Transform, online tools — and what changes in the conversion.
- How to convert GLB to STL for 3D printing
Free converters and the gotchas around scale, hollows and density.
- How to view a DXF file on phone or web
2D and 3D DXF viewers, free options for every platform.
- How to share a 3D model with someone who doesn't have CAD software
Five practical ways to send a 3D file that opens on the receiver's phone or browser.
Deep dives
- Draco compression explained — how to ship smaller GLB files
How Google's geometry codec shrinks 3D files 5–15x with negligible loss.
- PBR materials in GLB — a primer for 3D artists
What base color, metallic, roughness, normal and occlusion maps do, and how they combine.
- Best free 3D viewers in 2026 — an honest comparison
Browser, mobile and desktop picks for STL, GLB, STEP and the rest.