Intermediate
ERC-721 NFT Implementation — Check your understanding
Understand token IDs and metadata.
Developer Intermediate
6/6 — ERC-721 NFT Implementation — Check your understanding
Sanity test You should be able to explain to a buyer, a marketplace, and a teammate how ownership, approvals, metadata, and royalties work—and back it with tests and explorer links.
Trusted third parties are security holes.
Edge-case recall Know what happens if someone calls transferFrom on a contract without onERC721Received. Know whether paused state blocks burns or only transfers. Know how you’d rotate a royalty receiver.
Evidence If challenged, you can point to tests that cover approvals, receiver hooks, baseURI changes, and royaltyInfo. You can also point to events that make these actions observable.
Key points
- Explain why safeTransferFrom needs:ERC721Receiver and how you test it.
- Show how you cap:Supply, gate minters, and pause transfers without locking tokens forever.
- Describe how EIP-2981 is:Read by marketplaces and why it is advisory, not enforced.
- Prove your tokenURI scheme:Survives a baseURI change/freeze and how users can verify metadata integrity.