Hello there, mahesh5.

Setting up barcodes is currently unavailable. However, we have the SKU feature, which is used to help track your inventory items. I'll show you how:

1. From the Gear icon, select Products and services under Lists.
2. Click on Edit on an existing item or select New at the upper-right. 
3. Enter the SKU.
4. Click on Save and close.

You can also use one of our third-party apps that will help you integrate barcodes into your inventory. I'll be attaching these references that will help you in adding inventory products in QuickBooks Online and run reports to keep track of your sales and inventory status.

Should you have any other questions, just mention me in your reply or posts. Take care!