NFT Smart Contract Security Checklist

Verify that minting cannot exceed the advertised maximum supply under any circumstances.

Use ReentrancyGuard on mint functions to prevent callback-based minting exploits.

Ensure msg.value check cannot be bypassed and excess ETH is handled properly.

Implement per-wallet limits and verify they cannot be bypassed via contract calls.

Check Merkle tree implementation for vulnerabilities. Use OpenZeppelin's MerkleProof.

If using signatures for allowlists, include nonces and expiration timestamps.

Batch mint quantity multiplied by price must not overflow.

Use Chainlink VRF or commit-reveal scheme. Block hash is predictable by miners.

Prevent minters from predicting which token ID they will receive before reveal.

Provenance hash should be committed before mint starts and verifiable after reveal.

Verify token IDs are assigned correctly without gaps or collisions.

If revealing in batches, ensure each batch cannot influence future batch outcomes.

Use IPFS pinning service or Arweave to prevent metadata loss. Centralized servers are a rug risk.

Lock baseURI after reveal to prevent post-mint metadata manipulation.

Ensure tokenURI returns correct URI for all valid token IDs and reverts for invalid ones.

If constructing URIs dynamically, ensure no injection of malicious paths.

Implement contractURI for collection-level metadata on OpenSea and other marketplaces.

Use EIP-2981 for on-chain royalty info. Most marketplaces check this standard.

Royalty percentage should be capped at reasonable level (typically 10% max).

Royalty receiver should be an address you control. Consider using a splitter contract.

Implement OpenSea's Operator Filter Registry if you want to enforce royalties on supporting marketplaces.

Verify royalty math works correctly for both small and large sale amounts.

All administrative functions must have appropriate access control modifiers.

Two-step ownership transfer prevents accidental lockout from typos.

Owner should not be able to change critical parameters that could rug holders.

For fully decentralized collections, consider renouncing ownership after setup.

Have a way to withdraw ETH and accidentally sent tokens from the contract.

balanceOf, ownerOf, safeTransferFrom, transferFrom, approve, setApprovalForAll, getApproved, isApprovedForAll must all work correctly.

Transfer, Approval, and ApprovalForAll events must be emitted correctly.

Return true for ERC721, ERC721Metadata, and ERC165 interface IDs.

Must call onERC721Received on recipient contracts and revert if not accepted.

Transfers to zero address should revert. Burning should use a burn function.

Consider ERC721A for batch minting efficiency. It significantly reduces gas for multiple mints.

Pack storage variables efficiently. Use uint96 for token counters if under max.

Pre-compute string concatenations where possible. Avoid dynamic string operations.

Verify gas costs are acceptable for single and batch mints.

For very large collections, consider minting on demand rather than batch minting.