Here we'll look at how to use a .csv file to bulk upload items.
Login to your respective marketplace
Go into your marketplace manifests
From here if you're working on an existing marketplace manifest, then go ahead and open it OR if you're creating a new manifest, then go ahead and crate a new manifest.
Once you're in the manifest click the Add New Items tab
Click the Upload button
This would display a pop-up.
Here you can download the Upload Item Template csv file, by clicking the Items Template or directly click the Upload button in order to find and use your existing csv file