NFT Token Approvals: How to Check and Revoke Permissions

Every time you list an NFT for sale or connect your wallet to a new marketplace, you are usually asked to approve a smart contract. That single click grants the contract ongoing permission to move tokens on your behalf. Most of the time this is routine. Occasionally it is the exact mechanism a scam uses to empty a wallet. Understanding what a token approval actually is, and knowing how to check and revoke one, is one of the simplest ways to keep your NFTs safe.

What Is a Token Approval?

NFT standards like ERC-721 and ERC-1155 do not let a marketplace move your token directly. Instead, your wallet signs a message that tells the token’s smart contract: “this other contract is allowed to transfer tokens out of my wallet.” That permission is called an approval, and it lives on-chain until you remove it or it expires.

There are two common forms:

• Single-token approval, which lets a specific contract move one token you already own.
• setApprovalForAll, which lets a specific contract move every token you currently hold or will ever hold from that same collection.

Marketplaces default to the second option because it is more convenient. You approve once and can then list as many items from that collection as you like without signing again. Convenience is also what makes it risky if the wrong contract gets that permission.

Why Marketplaces Need This Permission

A marketplace cannot execute a sale unless it can move the NFT to the buyer the moment payment clears. Without an approval, you would need to manually sign a brand new transfer transaction for every single sale, which defeats the purpose of listing items in advance. So approvals are a normal, necessary part of how NFT trading works, not a red flag by themselves.

The problem is that an approval does not expire on its own and does not care who is asking. Once granted, it stays active until you cancel it, even years later, even if you never use that marketplace again.

How This Gets Exploited

Phishing sites built to look like real marketplaces often skip the part where they explain what you are signing. A pop-up window asks for a signature, the wording is vague, and the transaction actually requests setApprovalForAll for a malicious contract. Once that is confirmed, the attacker’s contract can transfer out every eligible NFT in that wallet at any time, with no further action needed from you.

This is different from a stolen private key. The wallet itself was never compromised. The owner simply granted a working permission to the wrong address, and the permission did exactly what it was designed to do.

How to Check Your Existing Approvals

Most wallets do not show you a list of every approval you have ever granted, so you have to check separately. A few reliable options:

• Block explorers such as Etherscan, Polygonscan, and Basescan have a free “Token Approvals” tool under each wallet address, reachable from the explorer’s token or security tab.
• Third-party dashboards like revoke.cash let you connect a wallet (read-only, view permissions) and see every active approval across several chains in one place.
• Some newer wallet apps now surface an approvals or permissions screen directly in settings.

Look for approvals granted to sites you no longer use, contracts you do not recognize, or collections you minted from once and forgot about. Those are the ones worth reviewing first.

How to Revoke an Approval

Revoking is itself an on-chain transaction, which means it costs a small network fee, but it is usually quick:

• Open the approvals tool on a block explorer or revoke.cash and connect the wallet in question.
• Find the approval you want removed and confirm the revoke action.
• Sign the transaction in your wallet and wait for it to confirm.

Revoking does not affect NFTs you already own or sales already completed. It only removes future permission for that specific contract to move your tokens.

Good Habits Going Forward

• Read what a signature request is actually asking for before approving, not just the name of the site.
• Review your approvals every few months, the same way you might review app permissions on a phone.
• Revoke access for marketplaces or mints you no longer use rather than leaving old permissions active indefinitely.
• Be extra cautious with urgent pop-ups asking for a wallet signature, especially from links in social media or direct messages.

Approvals are a normal part of how NFTs move between wallets and marketplaces, but they are worth understanding rather than clicking through automatically. If you are minting your own collection, Simple NFT Creator is built to keep the technical side straightforward on both iOS and Android, so you can focus on your art while still knowing what permissions you are granting along the way.