This viewer allows you to view a FBX, glTF, GLB file in your browser directly.
This app makes viewing 3D scenes and models quick and easy. This app also provides FBX file to glTF format conversion. You can download the zipped glTF file.
You can just open a FBX, glTF, GLB file to view from your computer or your Google Drive.

FBX (Filmbox) is a proprietary file format (.fbx) developed by Kaydara and owned by Autodesk since 2006. It is used to provide interoperability between digital content creation applications.
glTF (GL Transmission Format) is a file format for 3D scenes and models using the JSON standard.
GLB file format is a binary form of glTF that includes textures instead of referencing them as external images.