I am trying to build an in-app marketplace, such as stepN has.
stepN marketplace - https://m.stepn.com/
While I am researching how the stepN marketplace is built, I found something curious.
As I know, opensea uses metaplex auction house to list the NFTs. and so does the stepN marketplace.
So both them are escrowless, and on-chain.
I found that some of the items are both listed on the stepN marketplace and the opensea, but some of them are not.
I know we cannot upload the NFT both in the opensea and the magic eden at the same time, since magic eden is an escrow program.
But why some of them are both listed on the stepN marketplace and the opensea, but some of them are not?
Is it because stepN uses off-chain partially? what is happening behind the scene?
Any help would be appreciated.
As far as I know OpenSea list all the items that belongs into a correct set Metaplex Certified Collection (MCC). So it should grab and list all the NFTs that your collection has.
Sadly, I don't know how is the OpenSea algorithm that fetch the NFTs from an collection and how much time waits to fetch again the NFTs from a collection in order to detect new added NFTs.
So the main issue on why there are some NFTs that doesnt appear can be because the NFT doesnt have a collection attached to it or the Market didnt fetch the new NFTs that are added into the collection.
The fixes are: adding the NFTs into the collection or waiting till the market fetch the newly added NFTs respectively (this can take some time normally)