Will my materials and animations survive?

Yes, exactly. This is a container change, not a mesh conversion — the JSON and the binary buffer are repackaged unmodified.

It says my file references external files.

Your .gltf keeps its geometry or textures in separate files that were not dropped. Re-export from Blender with "glTF Embedded" or "glTF Binary".

Is the result smaller?

Yes — about a third smaller than an embedded .gltf, because the binary data is stored raw instead of Base64-encoded.

Is my model uploaded?

No. The parsing and rewriting happen in this tab. Models are frequently confidential — an unreleased product, a client’s part, a scan of something proprietary — and none of it is transmitted. Turn your Wi-Fi off and the tool keeps working.

Can I convert several models at once?

Yes — drop as many as you like, or a whole folder. Each keeps its original name with the new extension, and you can download them individually or as a ZIP.

glTF to GLB Converter — One File, Nothing Lost

Packs a glTF document into the binary GLB container. This is not a mesh conversion and nothing is recomputed: the JSON scene and the binary buffer are repackaged as they are, so materials, animation, skinning and extensions all survive untouched.

Why most converters get this wrong

A tool built on a general 3D library will load the glTF into a mesh and export it again. That round trip discards everything that is not geometry — PBR materials, animation clips, skin weights, morph targets, custom extensions — because the intermediate representation has nowhere to keep them.

Here the document is read as a document. The JSON is rewritten only where the container demands it (the buffer's uri is removed, since a GLB's buffer is the binary chunk), and the binary data is copied byte for byte. Round-tripping GLB → glTF → GLB gives you back an identical binary chunk.

Self-contained files only

A .gltf may keep its geometry in a separate .bin and its textures as separate image files. Those are not in the file you dropped and a browser cannot go and fetch them — that would be a network request, which this page does not make.

When that happens you are told exactly which files are missing, by name. The fix is to export with the "embedded" or "binary" option from whatever produced the model — Blender's glTF exporter offers both.

A glTF whose buffer is a data: URI is self-contained and packs perfectly.

Why GLB is usually the right choice

One file rather than three or more; no broken relative paths when it moves; roughly a third smaller than an embedded .gltf, because the binary data is not Base64-encoded. Every web viewer, <model-viewer>, Three.js, Babylon.js and every AR quick-look pipeline prefers it.

The case for keeping .gltf is that it is text, so you can read and edit the scene graph by hand.

Other names for this

Also searched as “gltf to binary gltf”, “pack gltf into glb”.

Questions

Will my materials and animations survive?: Yes, exactly. This is a container change, not a mesh conversion — the JSON and the binary buffer are repackaged unmodified.
It says my file references external files.: Your .gltf keeps its geometry or textures in separate files that were not dropped. Re-export from Blender with "glTF Embedded" or "glTF Binary".
Is the result smaller?: Yes — about a third smaller than an embedded .gltf, because the binary data is stored raw instead of Base64-encoded.
Is my model uploaded?: No. The parsing and rewriting happen in this tab. Models are frequently confidential — an unreleased product, a client’s part, a scan of something proprietary — and none of it is transmitted. Turn your Wi-Fi off and the tool keeps working.
Can I convert several models at once?: Yes — drop as many as you like, or a whole folder. Each keeps its original name with the new extension, and you can download them individually or as a ZIP.