This article expands on the safety principles explained in our Safety & Scams in Crypto hub.
When you first try to use a decentralized application, you might see a popup asking you to “approve” a token. This confuses many beginners because it looks like you’re just giving permission, but you’re actually giving another program control over your money. Most explanations skip over how much control you’re giving away and what happens if that program is malicious or gets hacked.
What a Token Approval Actually Is
A token approval is a transaction that gives a smart contract permission to move a specific token from your wallet without asking you again.
Here’s what happens: You own tokens in your wallet. A decentralized exchange wants to swap those tokens for different ones. The exchange can’t just reach into your wallet and take your tokens—blockchain wallets don’t work that way. Instead, you sign an approval transaction that says “this exchange contract can move up to X amount of my tokens.”
After you approve, the exchange can execute the swap by moving your approved tokens to complete the trade. You don’t sign a second transaction for the actual swap because you already gave permission.
This system exists because smart contracts can’t access your tokens without explicit permission. The approval is that permission. It stays active until you revoke it or until the approved amount runs out.
Most applications ask you to approve either the exact amount you want to use right now or an unlimited amount, so you don’t have to approve again every time you use that application. Unlimited approvals are convenient but risky.
What Token Approvals Are Not
An approval is not the same as sending tokens. When you approve, your tokens don’t move anywhere yet. They stay in your wallet. You’re just creating a rule that allows a specific contract to move them later.
An approval is also not a one-time permission. Once you approve a contract, that permission stays active. If you approve unlimited access, the contract can keep moving your tokens days, weeks, or months later. Many beginners think the approval expires after they finish using an application. It doesn’t.
Approvals are not needed for the native cryptocurrency on each blockchain. You never approve Ethereum (ETH) itself, only tokens that exist on top of Ethereum, like USDC or DAI. You never approve Bitcoin. You only approve tokens that follow certain standards, like ERC-20 tokens on Ethereum.
An approval doesn’t mean the application will definitely steal your tokens. Legitimate exchanges and applications need approvals to function. The problem is that malicious contracts use the exact same permission system.
What Can Go Wrong
The biggest risk is approving a malicious contract. If you approve a fake token swap site or a scam application, you’ve just given that contract permission to drain your wallet. The contract can take your tokens immediately or wait months before doing it.
This is different from most scams. Usually, when you send cryptocurrency to a scammer, you lose what you sent, but nothing more. With approvals, you can lose everything you approved, plus any future tokens of that type that you receive later if you gave unlimited approval.
Hacked applications create the same problem. If you approved a legitimate application and that application gets hacked later, the attacker can use your old approval to take your tokens. Your approval doesn’t know the application got hacked. It just keeps working.
Abandoned applications with old approvals are also a risk. You might have approved a token swap two years ago and forgotten about it. That approval still exists. If someone exploits a vulnerability in that old contract, they can access your tokens through your old approval.
Unlimited approvals are particularly dangerous. Many applications ask you to approve unlimited amounts instead of exact amounts. This saves you from having to approve again later, but it means the contract can take all of your tokens of that type, not just what you planned to use.
Some beginners think their wallet will warn them before an approved contract takes their tokens. It won’t. Once you approve, the contract can move your tokens without your wallet showing any warning or asking for confirmation. From your wallet’s perspective, you already gave permission.
Common Beginner Mistakes
Approving without reading what you’re approving. Approval popups often show technical details like contract addresses and hexadecimal numbers. Beginners often click approve without understanding what they’re agreeing to. The key information is: which contract you’re approving, which token, and how much. If you can’t verify that the contract address matches the legitimate application, don’t approve.
Thinking approvals expire automatically. Your approvals stay active forever unless you manually revoke them or until you’ve used up the approved amount. If you approved 100 USDC and only used 50, the remaining 50 is still approved. If you approved unlimited USDC, that approval never decreases no matter how much you use.
Approving tokens on unfamiliar websites. If a website asks you to approve tokens before you’ve even connected your wallet properly or before you understand what the application does, that’s suspicious. Legitimate applications explain what they do before asking for approvals.
Giving unlimited approvals without understanding why. Applications default to unlimited approvals because it’s more convenient for frequent users. But if you’re only using an application once, or trying something new, approve the exact amount you need. You can always approve more later.
Not keeping track of old approvals. After months of using different applications, you might have dozens of active approvals scattered across various contracts. You can check your active approvals using tools like Etherscan’s token approval checker or Revoke.cash. If you don’t recognize an approval or don’t use that application anymore, revoke it.
Confusing token approvals with wallet connection. When you connect your wallet to a website, you’re just letting the website see your public address and balances. That’s relatively safe. Approving tokens is different—it gives the website’s contract power to move your money. These are two separate actions. Connection lets them look. Approval lets them take.
Trusting approvals because they’re common. Yes, you need to approve tokens to use decentralized exchanges and most DeFi applications. But scammers know beginners are getting used to approving things, so they disguise malicious approval requests as normal ones. Just because approvals are common doesn’t mean every approval request is legitimate.
Not revoking approvals after getting suspicious. If you approved a contract and later realized the website seemed sketchy, revoke the approval immediately. Don’t wait to see what happens. Revoke.cash and similar tools let you cancel approvals. There’s usually a small network fee to revoke, but it’s worth it.
Continue Learning
Understanding approvals is part of protecting yourself in decentralized systems. To go deeper, learn about how to verify you’re interacting with legitimate contracts and not fake copies. Study how to check active approvals on your wallet and how to revoke them safely.
You should also learn about the different types of approvals. This article covered ERC-20 token approvals, but NFTs use a different system called “setApprovalForAll” that works differently and has its own risks.
The core skill here is understanding that blockchain transactions are permanent and irreversible. Once you approve something malicious, your tokens can be taken without further warning. Learning to verify contracts, check approvals regularly, and approve only what you need will prevent most approval-related losses.
Disclaimer: This article is for educational purposes only and is not financial advice. Cryptocurrency is highly volatile and risky. Only invest money you can afford to lose. Past performance is no guarantee of future results. Always do your own research and consider consulting a qualified financial advisor.
