NFT Marketplace Integration 3

Question 1

What is the main advantage of using a marketplace aggregator (like Gem or Blur) integration over a single marketplace API?

Accepted Answer

It pools liquidity and listings across multiple marketplaces for best price/availability

Answer

Aggregators combine order books from several marketplaces so buyers can sweep the lowest-priced listings in one transaction.

Question 2

When implementing a 'sweep the floor' feature, what technique reduces gas across many purchases?

Accepted Answer

Batching multiple fulfillments into a single transaction

Answer

Batch fulfillment executes several order completions in one transaction, amortizing base gas costs across all items.

Question 3

A marketplace shows a stale price after an item sells. Which integration practice best prevents this?

Accepted Answer

Listening to on-chain events (e.g., OrderFulfilled, Transfer) to invalidate cached orders

Answer

Subscribing to fulfillment and transfer events lets the integration remove or update orders the moment state changes on-chain.

Question 4

What does 'order cancellation' on-chain typically require from the seller?

Accepted Answer

A transaction that invalidates the order's nonce or hash, costing gas

Answer

On-chain cancellation submits a transaction marking the order hash/nonce as filled or cancelled so it can no longer be fulfilled.

Question 5

When integrating WETH for offers/bids, why is WETH used instead of native ETH?

Accepted Answer

ERC-20 WETH supports the approve/transferFrom flow needed for off-chain bids

Answer

Native ETH lacks the ERC-20 allowance mechanism, so wrapped ETH is used to enable pre-approved bid fulfillment without the bidder being online.

NFT Development Practice Test