IERC721compliant

IERC721compliant is a term used to describe a smart contract that conforms to the ERC-721 non-fungible token standard as defined by the IERC721 interface. A compliant contract implements the core NFT semantics: unique token identifiers, ownership tracking, transfer mechanics, and token approvals, enabling interoperable interactions with wallets, marketplaces, and other contracts.

The core requirements of IERC721 compliance include implementing the external functions and events specified by the IERC721 interface. Essential functions are balanceOf(address owner) external view returns (uint256); ownerOf(uint256 tokenId) external view returns (address); safeTransferFrom(address from, address to, uint256 tokenId) external; safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external; transferFrom(address from, address to, uint256 tokenId) external; approve(address to, uint256 tokenId) external; setApprovalForAll(address operator, bool approved) external; getApproved(uint256 tokenId) external view returns (address); and isApprovedForAll(address owner, address operator) external view returns (bool). Events that must be emitted include Transfer(address from, address to, uint256 tokenId), Approval(address owner, address approved, uint256 tokenId), and ApprovalForAll(address owner, address operator, bool approved).

In addition, IERC721 compliance typically requires implementing ERC165 supportsInterface, returning true for the IERC721 interface id 0x80ac58cd and for ERC165 itself (0x01ffc9a7). Optional extensions such as IERC721Metadata (name, symbol, tokenURI) and IERC721Enumerable (optional enumeration) are commonly but not universally implemented.

Achieving IERC721 compliance ensures compatibility with standards-based tooling and ecosystems, enabling tokens to be recognized, transferred, and audited by wallets, exchanges, and decentralized applications that rely on standard ERC-721 behavior.