JSON exporter for Open Asset Import Library to make 3D models accessible from JS/WebGl
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JSON exporter for Open Asset Import Library

Convert files in 40+ 3D file formats, including Collada, 3DS, OBJ, LWO, FBX, Blender, X, STL, PLY, MS3D, B3D, MD3, MDL, DXF and IFC to plain json.

Convert models online here. (Select JSON as output format)

Download Windows binaries here. (v2.0, October 2013)



assimp2json is a command line tool designed to expose the import capabilities of assimp, the Open Asset Import Library to WebGl developers. The tool takes a single 3d model as input file, imports it using assimp and converts the result to json.

assimp2json is platform-independent, its only dependency is assimp itself.

Output Format

The output format is a one-by-one translation of Assimp's C datastructure , with a few changes to make the resulting json look more natural. All fields are lower-case and the prefixes (such as m, pc, ..) are omitted. Array lengths are not written as this information is implicitly given. Empty arrays are not written at all, i.e. a node without children doesn't have an empty children:[] field.

The /samples folder contains some sample assimp.json files.

assimp.json files carry a little format header in the JSON root element. This allows them to be disambiguated from other JSON-based 3D formats (such as Three.JS scenes). The numeric value specifies the assimp2json format version in (major, minor, revision) format. Currently, only 100 is defined.

 "__metadata__": {
 	 "format" : "assimp2json"
 	,"version": 100


The build system for assimp2json is CMake. To build, use either the CMake GUI or the CMake command line utility. Note: make sure you pulled the assimp submodule, i.e. with git submodule init && git submodule update


$ assimp2json [flags] input_file [output_file] 

(omit the output_file argument to get the json string on stdout)

Invoke assimp2json with no arguments for detailed information.

Future Plans

I plan to build a proper content pipeline for WebGl assets based on assimp, assimp2json, possibly OpenCTM, WebP and Crunch/DXT to be able to preprocess 3D assets and their textures for fast streaming. Stay tuned, or drop me a note if you want to help out.