OpenSea is decentralized, so we never escrow or hold your items. As a result, if this is your first time selling an NFT, you need to complete 2 free (plus gas) transactions:
- To initialize your account for making sell orders, which only needs to be done once for your account.
- To allow OpenSea to access your item (or all items in the collection, if the collection supports it) when a sale occurs.
After those, you'll see a signature request to finalize your listing. In the future, as long as the item was approved in step 2 above, you won't have any transactions at all, only a signature. This is how we can (almost) achieve gas-free listings.
The information above is also outlined under Instructions on the Sell page.