eBay connection
Connecting eBay Sandbox, and what "API vs. CSV" means.
API vs. CSV — what's the difference?
CSV export produces a file you review and upload yourself through eBay's own tools (or another marketplace's tools). Reseller Express never talks directly to the marketplace in this path.
API connection means Reseller Express talks directly to eBay's own systems, using an authorization you explicitly grant, to prepare and publish a listing without you manually uploading a file. This path currently runs only against eBay's Sandbox (test) environment as part of a controlled testing phase — not eBay's live marketplace.
Connecting eBay Sandbox
When available to your account, connecting starts an authorization flow hosted by eBay itself. You'll be asked to grant specific permissions (called scopes) — Reseller Express only requests what it needs to prepare and publish listings on your behalf, and you can disconnect at any time.
Why a connection might require verification
Marketplaces like eBay require developers and applications to go through their own approval process before an API connection can be used, even in a Sandbox/testing environment. If your account shows a connection as pending or unavailable, this is usually why — it's not something Reseller Express can bypass.