What’s the best tool for cropping / center photos automatically ?

I have a small business of selling things on internet. I have to take a lot of picture everyday and not all of them are perfect and I need to resize them to be sure the subject is well centered.

All of my pictures are taken in a photo box. So I'm searching a tool that could allow me to automatically center / resize them all at once so I won't have to do it myself, I just want to automate this process, and if there is also a possibility to "whiten" the background that would be even better.

thanks in advance for your answers.