Our Fulfillment By Amazon (FBA) integration makes it easy to check on your FBA stock levels on a per-order basis.
As long as you have 'FBA' selected as the 'Ship From' value on an order, ShipStation can display the "Total Supply" and "In Stock" values as reported by FBA for the SKUs (or Fulfillment SKUs) associated with those line items.
Here's what this looks like on the Order Detail screen:
... and within the Order Sidebar:
Knowing these FBA inventory levels before you send fulfillment requests can save you time and clicks!