What Is Whitelist?

In token sales (ICO, IDO) and NFT mints, a whitelist identifies the wallet addresses granted the right to take part in the sale or to buy earlier and sometimes at a more favorable price. Projects may tie getting onto this list to conditions such as community activity, early support or identity verification (KYC). The smart contract checks whether the address is on the list during the transaction; to reduce gas costs for long lists, a Merkle proof is generally used.

In a security context, many crypto exchanges offer an address whitelist feature that ensures withdrawals can be made only to pre-registered addresses. When a new address is added, a waiting period is often applied. This way, even if an account is compromised, it becomes harder for an attacker to immediately withdraw funds to their own address. Some smart contracts also allow only approved addresses to call certain functions.

In the industry, the terms allowlist instead of whitelist and denylist instead of blacklist are increasingly used. Messages that ask for a fee to get on a whitelist, or that request a private key or recovery phrase, are a common phishing method; such requests outside official channels should not be trusted.