3D OBJ Viewer is a free Android application developed by otoone_dev that allows users to view 3D models on their mobile devices. The app displays 3D objects that can be rotated in the direction of the device, providing a unique and interactive experience. To use the app, users must have the necessary "obj file" and "mtl file" and textures located in the same folder. These files can be created from popular 3D software such as Blender or Metasequoia, or obtained from the internet.

The app includes several features such as stereoscopic mode, view reset, automatic rotation, light on/off, and texture mode. Users can also control the back face culling mode and use touch controls to rotate and move the object. The app also includes TGAReader and DDSReader, which allow users to read TGA and DDS image files. Overall, 3D OBJ Viewer is a simple but effective tool for viewing 3D models on mobile devices.