The 3D formats you meet most often are GLB and glTF (web and games), STL (3D printing), OBJ (general model exchange) and PLY (scans). Each stores geometry, but they differ in what extra information they carry and what they are designed for. The 3D model viewer opens all of them.
Here is each one, in plain terms.
GLB and glTF, the web standard
glTF is a modern, open format built for fast loading in browsers, games and augmented reality. GLB is its single-file binary version, which bundles geometry, materials and textures together, while glTF (.gltf) is JSON text that often links to separate files. If you are working with 3D on the web or in a game engine, this is the format you will see most. There is a fuller comparison in GLB vs glTF.
STL, the 3D printing format
STL describes a model as a mesh of triangles, with no colour or texture. It is simple and supported by virtually every 3D printer and slicer, which is why it dominates 3D printing. If you download a model to print, it is almost always an STL. See how to view an STL file for more.
OBJ, the universal exchanger
OBJ is one of the oldest 3D formats and is exported by nearly every modelling tool. It stores geometry as plain text and keeps materials in a companion .mtl file. Because it is so widely supported, OBJ is a common way to move a model between two programs that share little else.
PLY, the scanner’s format
PLY stores geometry and, often, per-vertex colour. That makes it the natural choice for 3D scans and photogrammetry, where colour captured from the real object is baked into the mesh. Open a PLY and you will frequently see the scanned colours along with the shape.
A quick comparison
| Format | Best for | Carries colour/texture? | One file? |
|---|---|---|---|
| GLB | Web, games, AR | Yes, embedded | Yes |
| glTF | Web, games, AR | Yes, often in side files | Often no |
| STL | 3D printing | No | Yes |
| OBJ | Model exchange | In a side .mtl file | Usually no |
| PLY | Scans | Per-vertex colour | Yes |
See any of them
Whichever you have, you can open it without installing anything. Drop your file into the 3D model viewer to rotate it, read its size and triangle count, and take a screenshot, all in your browser, with nothing uploaded.