A GLB file is a 3D model stored as one binary file. It is the binary packaging of glTF — the open 3D interchange format maintained by the Khronos Group — which means a .glb carries the same data a .gltf does: geometry, PBR materials, textures, cameras, animation. The only difference is the container. Instead of a JSON document plus a folder of external buffers and images, everything is packed into a single self-contained file.
That single-file design is why GLB has become the default way 3D models travel. If you received a .glb from a CAD export, a 3D artist, or an asset store, it is the complete model — nothing else needs to come along with it, and any glTF-compatible tool can open it.
What a GLB file contains
A GLB file has three parts laid out one after another in the binary:
- A short header identifying the file as glTF binary and giving the version.
- A JSON chunk describing the scene: the node hierarchy, which meshes exist, how materials are defined, which textures apply where.
- A binary chunk holding the heavy data itself — vertex positions, normals, animation data, and the texture images.
This layout is written into the glTF specification itself, so every GLB file has the same structure no matter which tool exported it. The practical consequence: nothing external is required. The textures live inside the file; the geometry lives inside the file. A GLB attachment or download is the whole model, which is what makes it reliable to move between people, tools, and pipelines.
GLB is binary glTF — the name is literal
GLB is not a competing format or a vendor’s variant. The binary container is defined in the glTF specification, and the name is usually read as “GL Binary” — the binary form of GL Transmission Format. Converting a .gltf to a .glb (or back) is repackaging, not re-encoding: geometry precision, material definitions, and texture pixels are identical on both sides, and tools do it constantly. Blender exports either format natively, and most conversion utilities treat the two as the same model in two different envelopes.
GLB vs .gltf: the differences that matter
Because the data is identical, every real difference between the two containers is about packaging — and packaging decides where each one fits.
| GLB (binary) | .gltf (JSON) | |
|---|---|---|
| What it is | One self-contained binary file | JSON text, usually plus a .bin buffer and separate texture images |
| Textures | Embedded in the file | External image files (or base64-embedded, which inflates the JSON) |
| Sharing | One file — nothing to leave behind | A folder of files — breaks quietly if assets get separated |
| Reading by hand | Binary; inspect with tooling | JSON text — readable and diff-able in version control |
| Size | Usually the most compact single file | Comparable payload; base64 embedding adds roughly a third |
| Best for | Anything that travels as a deliverable | Pipelines that want the assets split |
The short version: default to GLB whenever the file leaves your machine — uploads, attachments, client handoffs, asset pipelines — and choose .gltf when a specific process wants the JSON and the binary assets separate.
How to open a GLB file
In a browser viewer — fastest
The standard free option is Don McCurdy’s glTF-Viewer. Drag the file onto the page and it renders as an orbitable 3D view in seconds. The tool’s real purpose is inspecting and debugging glTF files — wireframe and material modes, environment-lighting swaps to check how materials behave — and it reads the file in your browser rather than uploading it to a server. As of 2026-09 it is free and open source. For “is this the right model, is it textured correctly,” it is exactly the right tool.
In Blender — free desktop
Blender imports GLB natively (File → Import → glTF 2.0) and is free and open source. Choose this route when you also need to edit, inspect deeply, re-export, or convert the model — you get the file into a full 3D suite rather than a preview window.
On a hosting platform — for sharing
Sketchfab gives an uploaded GLB a shareable page with a polished embedded player: camera animation, annotations, lighting presets. Its purpose is hosting and showcasing models, not inspecting them. Worth knowing before you upload: the model leaves your device and sits on the service’s servers, free uploads are geared toward public models, and it is freemium as of 2026-09 — check the current terms if privacy matters for your file.
Through a converter — for other formats
Sites such as imagetostl and Convert3D exist to convert between 3D formats — GLB to glTF, OBJ to GLB, FBX to GLB. Their preview pane looks like a viewer, but its real job is confirming the conversion worked before you download. Conversion is also an upload: the file goes to the service’s servers.
What to do with a GLB once it is open
Viewing answers “what is this model?” — and often that is step one of a larger job. If the file is a product model and the end goal is imagery of it — listing photos, marketing stills, launch visuals — a viewer is the starting line rather than the finish: viewport screenshots record the model under generic lighting against a bare background, which reads as a preview rather than a photo. The workflow this site is built around takes over from there: Shotshot imports GLB and glTF with the file read locally into a project on your device, lets you frame views of the model in 3D, and uses those captured views as references for generating finished product images.
Frequently asked questions
The short version: GLB is glTF in a single binary file, opening one takes any glTF viewer, and the packaging changes nothing about how the model looks. The answers below cover the details.