What Is a .gltf File? .gltf Format, MIME & How to Open

Quick facts

Extension.gltf

File typeglTF 3D Model

MIME typemodel/gltf+json

Category3D Model

Charset—

CompressibleYes

Format familygltf

What is .gltf

What is a .gltf file?

A .gltf file is a glTF 3D Model — JSON-based runtime 3D asset format.

In the mime-db registry it maps to model/gltf+json, and it is marked as compressible. When serving .gltf over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to model/gltf+json and is used by JSON among others — and is delivered over HTTP via the Content-Type header.

How to open .gltf files

Use Blender or three.js to open and edit .gltf files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: model/gltf+json

Common software that reads/writes .gltf:

Blenderthree.jsBabylon.js

Relation chain

.gltfextension of

format

gltfserved as

mime type

model/gltf+jsonsent via header

http header

Related extensions

Related MIME types

Related programming languages

JSON

.json .4DForm .4DProject

Common uses

3D printing
Game assets
CAD and design exchange

How to edit .gltf files

Open the file with Blender, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .gltf files

Create a new file and save it with the .gltf extension, or export this format from Blender.

Frequently asked questions

What programs can open .gltf files?

Common options include Blender, three.js, Babylon.js. You can also open many of these files with built-in viewers or a browser.

How do I create a .gltf file?

Create a new file in any text editor or the app that owns the format and save it with the .gltf extension.

What is the relationship between .gltf and the model/gltf+json MIME type?

model/gltf+json is the media type identifier used for .gltf files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-08-18

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