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GLTF
What is a GLTF file?
The 3D format for the web. Geometry, materials and animation in one JSON file.
What GLTF is
GLTF is a plain-text format you can open in any editor. It stores shapes and coordinates rather than pixels, so it stays sharp at any size — a logo scaled to a billboard loses nothing. It is used for the web and handing a finished file over.
The extension is .gltf, and the full name is GL Transmission Format. Both matter less than what the file can hold, which is what the rest of this page is about.
Where GLTF came from
Khronos Group published it in 2015. The specification is glTF 2.0.
Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.
The specification is public
Anyone can implement it without asking permission or paying a licence, which is why it turns up in so many programs and why files written twenty years ago still open.
Nothing is thrown away
GLTF stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.
It can hold more than one frame
GLTF can store an animation rather than a single still. That is worth knowing before converting one: a target that holds one frame keeps the first and drops the rest, usually without saying so.
What opens GLTF
Blender, three.js and Babylon.js read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
Every current browser reads it.
That makes it a safe thing to put on a page or attach to a message without wondering what the other end has installed.
It is a working format
GLTF is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.
The facts, in one place
| Extension | .gltf |
|---|---|
| Media type | model/gltf+json |
| Published by | Khronos Group |
| First published | 2015 |
| Specification | glTF 2.0 |