GLB vs glTF: packaging the same scene

GLB is the binary container for a glTF asset. A .gltf file stores the scene description as JSON and can refer to embedded or external resources. The choice changes packaging; it does not by itself repair missing geometry or recover materials that a reader omitted.

A measured pair

Our tetrahedron exports to a 676-byte GLB and a 1232-byte JSON glTF. In this JSON example, the geometry buffer is embedded in a data URI. Both files read back as four triangles with dimensions of approximately 0.01 × 0.01 × 0.01 metres, representing the original 10 mm part.

This is a small geometry-only sample. Its size difference is not a prediction for a scene with textures, several buffers, or different compression extensions.

External resources are part of the input

A JSON file that names an external .bin file has not included those bytes. The same applies to external texture images. This reader does not offer a complete multi-file resource import workflow, so changing the extension or uploading just the JSON cannot make missing resources appear. Export a self-contained asset from the source application when that fits your task, or use a tool that accepts the full resource set.

The Khronos glTF specification defines the JSON structure, binary container, and metre-based coordinate convention. This site's model conversion handles a supported geometry subset. It does not preserve every material feature, texture, animation, skin, camera, or light permitted by the specification.

Verify the part that matters

For a geometry transfer, check triangle count, dimensions, and visible shape after conversion. If the receiving application needs animation or textured appearance, verify those properties there with the full source asset. A successful geometry report is not a certification that the rest of the scene survived. The paired downloads show exactly what this example includes.