What is a .obj file? (OBJ)

OBJ is a widely supported 3D model format that stores geometry plus optional texture coordinates, and it can reference materials in a companion MTL file. It is a common interchange format between 3D applications.

What is a .obj file used for?

An OBJ is plain text listing vertices, texture coordinates and faces. It can point to an accompanying .mtl file that defines colours and textures.

Because it is simple and text-based, almost every 3D tool imports and exports OBJ, making it a reliable way to move models between programs.

It does not store animation or rigging, so for game and film pipelines richer formats like FBX or glTF take over.

How to open a .obj file

The .obj format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .obj file.

Windows

Blender
Windows 3D Viewer
MeshLab

macOS

Blender
Preview (view)
MeshLab

Linux

Blender
MeshLab

Web

Online 3D viewers

How to convert a .obj file

You can convert a .obj file to STL, FBX, GLTF using a conversion tool or the export menu of an app that opens it.

.obj file signature (magic bytes)

Programs recognise a .obj file by the bytes at the start of the file, not by its name. These are the signatures for OBJ.

Hex signature	Offset	Note
(no fixed signature)	0	plain text; lines often start with 'v ' or '# '

See the full magic-numbers reference for every format.

Frequently asked questions

What is a .obj file?

Why is my OBJ model missing its colours?

OBJ stores textures and materials in a separate .mtl file, plus image files. Make sure those travel alongside the .obj.

Related formats

Sources

Details on this page were checked against authoritative references:

Wikipedia: Wavefront .obj file