ERC-721 NFT Implementation — Key concepts
Understand token IDs and metadata.
Why it matters ERC-721 compatibility is binary: wallets either understand your contract or they don’t. Emitting the exact events and keeping tokenURI predictable ensures discoverability. Roles and supply limits keep mints sane; lean hooks prevent reentrancy surprises.
Blockchains solve coordination problems, not just financial ones.
Design lens Decide early whether metadata is mutable, whether tokens can be paused or soulbound, and how royalties are signaled. Each choice affects marketplaces, so document it. Think about how metadata is cached by aggregators and what happens if you rotate a baseURI.
User trust Buyers rely on predictable ownership semantics. Document how approvals work, how to revoke them, and whether your collection enforces any transfer restrictions. Clear language in the contract and docs prevents disputes later.
Ops and support Support teams need answers to “why doesn’t my image show?” and “who can mint?” Bake those answers into the contract (events, view helpers) and into runbooks so issues are easy to debug in production.
- ERC-721 surface:BalanceOf, ownerOf, safeTransferFrom, approve/setApprovalForAll, tokenURI, supportsInterface.
- Metadata:BaseURI patterns, per-token overrides, on-chain vs off-chain JSON; how marketplaces cache it.
- Access control:Roles for mint/burn/pause; max supply; soulbound or non-transferable rules.
- Events:Transfer, Approval, ApprovalForAll must fire correctly for indexers and wallets.
- Safety:SafeTransferFrom receiver checks; reentrancy on hooks; blocking mints/transfers when paused.
- Royalties:EIP-2981 vs custom payout splits; why royalties are not enforced on-chain by the standard.