OneCart has two ways to add many inventory items into OneCart, Bulk Upload, and Inbound Stocks.
The main difference between the two is that Bulk Upload will overwrite the quantity that exists in OneCart. Inbound Stocks will add onto the balance in OneCart.
Eg: Let's say you have a SKU called ABC123 in OneCart, with an existing quantity in OneCart of 10 pieces, and you have a CSV which contains ABC123 and a quantity of 20,
If you use Bulk Upload, the system will overwrite the quantity in OneCart, so the new stock on hand in OneCart (and the stock level pushed out to all platforms if auto-update is toggled on) will be 20.
If instead you use Inbound Stocks, the system will add 20 pieces to the existing quantity of 10, so the new stock on hand will be 30 (and this will be pushed out to all platforms if auto-update is toggled on).
Sellers generally use Bulk Upload when doing a stock check and want OneCart to take all new quantities based on that stock check, and also when adding new items.
Sellers generally use Inbound Stock when "receiving" new shipments from suppliers, so these are items that already exist, and you just want to add on the stock levels from the latest shipments.
OneCart supports both ways to help you in your business workflow however you prefer. We hope this article was helpful in explaining the difference!