It is a handy tool to convert 3D models from one file format to another (i.e. FBX to OBJ or OBJ to STL for 3D printing, DAE to JSON for use with WebGL, ..).
Supported input file formats include 3DS, FBX, Blender, OBJ, DXF, LWO, STL, PLY and more than 25 others. Output formats include Collada, 3DS, X, OBJ, PLY, STL (Text and Binary), JSON (Assimp2Json) and more. You can upload up to 5 files with a total size of 50 MiB.
This service is forever free.