Can i find offline 3d viewer software which uses in grabcad

If you have access to the files and re-saving them, I would suggest 3D PDF if you want to view the files anywhere (with adobe)

Otherwise, you could download a free trial for Fusion 360, or SW, etc.. and work from there.

The files are viewable from online/offline

Dear ML

If you noticed any assembly drawing in grabcad it facilitate to view all parts. whether part is present there or not you can browse all parts from single assembly drawing.

Thanks & Regards