The QBB file is a backup file used in QuickBooks Desktop (QBDT). Right now, there is no direct way of opening and importing this into your existing QuickBooks Online (QBO) account. You'll need to open the file in the Desktop version, then import it to QuickBooks Online. Find the steps to open a qbb file without QuickBooks. Here are steps to import QuickBooks qbb file into excel and how to restore them.