How can add barcode to the invoice for each item

Hi there, @tahahajjoul.

Currently, QuickBooks Online doesn't have a direct connection to the barcode scanner and don't have the option to add one to the products. Although, we've got you some third-party applications that have this kind of functionality and can sync with QBO. You can go to the Apps menu in the left pane and search for any barcode scanning apps. 

You may consider checking our blog website to keep you up-to-date on the feature release.

I've added this reference page to help you manage your lists, sales forms, and items in QuickBooks Online: Adding Products and Services, Customers, and Vendors to Lists. This also contains video tutorials such as setting up products and services or customer lists.

I'll be here if you have other questions with QuickBooks Online. Don't hesitate to tag my name in the comment section. I'd be happy to help. Take care.

@tahahajjoul 

You may need an inventory management app to do so.