QuickBooks Online

Good morning, @chippewafoundry. 

Welcome to the QuickBooks Community. I'd be more than happy to tell you about custom fields in QuickBooks Online. 

You can use custom fields with the Essentials, Plus, and Advanced versions of QBO. Here's a list of what you can add custom fields to based on the product you're using: 

• Essentials: Sales Forms
• Plus: Sales Forms and Purchase orders
• Advanced: You can create custom fields for almost anything. 

Check out these guides at the beginning of this post to learn how to add them and for additional details. 

I hope this helps in your case. Feel free to come back and let me know how these steps worked for you. Have an amazing day! 

@chippewafoundry 

Custom Fields are supported in QuickBooks Online for the following transaction types:

Invoices
Sales Receipts
Refund Receipts
Credit Memos
Estimates

You can utilize a 3rd party tool to import data with custom fields. But due to the limitation of the tool at his time, you can only able to import up to 3 custom fields.

https://transactionpro.grsm.io/qbo

Another option, purchase a 3rd party service to convert your data from QBD to QBO with up to 3 custom fields.

I watched the guides, but I don't see the add field option in inventory items.

Thanks,

that confirms what I'm seeing with inventory items.