Stitch Labs, ChannelAdvisor, Shopify, BigCommerce, Ecomdash, SkuVault and Finale Inventory will let you check on their stock counts while you're shipping orders within ShipStation. These counts can give you additional peace of mind as you ship, without having to switch between ShipStation and another website to check availability.
Once set up, you'll see the selling channel's provided stock counts on both the Order Details screen...
... and the Order Sidebar's Item(s) Ordered section:
Both the counts and the terminology come from the selling channel -- ShipStation is just acting as a window to give you visibility into information managed by that partner.
This visibility is easy to set up! You simply set the Inventory Source for the Ship From Location.
Set Inventory Source
Head to your Account Settings (the wrench icon in the upper right).
Next, select Shipping and then Ship From Locations from the sidebar on the left.
Click Edit for one of your Ship From Locations.
Select your desired Inventory Source from the drop-down menu.
Repeat as needed for any Ship From Location that needs this selling channel inventory visibility.
As long as you have the right Ship From value selected for your order, ShipStation will know which selling channel to use as an Inventory Source for these counts!