NFT Marketplace Integration 3 — Questions and Answers
Question 1: What is the main advantage of using a marketplace aggregator (like Gem or Blur) integration over a single marketplace API?
- It pools liquidity and listings across multiple marketplaces for best price/availability (Correct answer)
- It guarantees zero gas fees
- It mints NFTs automatically
- It hides the seller's wallet permanently
Correct answer: It pools liquidity and listings across multiple marketplaces for best price/availability
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?
- Batching multiple fulfillments into a single transaction (Correct answer)
- Sending one transaction per NFT sequentially
- Disabling royalties
- Minting placeholder tokens first
Correct answer: Batching multiple fulfillments into a single transaction
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?
- Listening to on-chain events (e.g., OrderFulfilled, Transfer) to invalidate cached orders (Correct answer)
- Polling the image URL
- Refreshing only once per day
- Trusting the buyer to report sales
Correct answer: Listening to on-chain events (e.g., OrderFulfilled, Transfer) to invalidate cached orders
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?
- A transaction that invalidates the order's nonce or hash, costing gas (Correct answer)
- Just deleting the listing from the website
- Emailing the marketplace
- Sending the NFT to a burn address
Correct answer: A transaction that invalidates the order's nonce or hash, costing gas
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?
- ERC-20 WETH supports the approve/transferFrom flow needed for off-chain bids (Correct answer)
- WETH is cheaper to send
- WETH cannot be lost
- Native ETH is banned on marketplaces
Correct answer: ERC-20 WETH supports the approve/transferFrom flow needed for off-chain bids
Native ETH lacks the ERC-20 allowance mechanism, so wrapped ETH is used to enable pre-approved bid fulfillment without the bidder being online.
Question 6: Which is a correct way to verify an NFT's authenticity before listing it on an integrated marketplace?
- Confirm the contract address matches the official verified collection (Correct answer)
- Check that the image looks nice
- Trust the seller's username
- Verify the token has a long name
Correct answer: Confirm the contract address matches the official verified collection
Since anyone can copy artwork, the on-chain contract address is the authoritative check against spoofed collections.
Question 7: What is a key reason to support multiple wallet providers (e.g., via WalletConnect) in a marketplace integration?
- It broadens user access across mobile and desktop wallets through a unified protocol (Correct answer)
- It increases royalty percentages
- It removes gas fees
- It speeds up block times
Correct answer: It broadens user access across mobile and desktop wallets through a unified protocol
WalletConnect provides a standard bridge so the marketplace works with many wallets without custom code for each.
NFT Marketplace Integration 3
What is the main advantage of using a marketplace aggregator (like Gem or Blur) integration over a single marketplace API?