Converting 3D models

Hi, I need 3D models in OBJ format with textures (baked png file), I'm getting free models online but a good majority are fbx, blender, stl which limits my selection. I can convert to OBJ using some online converters but not the textures sadly. I've looked into blender but the baking process is far too complex for me.
Are there any good free converters you would recommend if its even possible?