Token approvals let an application or smart contract spend specified tokens from a crypto wallet. They make decentralized exchanges and other DeFi services usable without sending funds to an application first. However, a permission that remains active can become a security problem if the approved contract is malicious or compromised.
The practical question is not merely whether a wallet is connected to a website. It is which address can spend which token, on which network, and up to what amount.
What happens when you approve a token?
On 
Ethereum market price and chart and other compatible networks, an ERC-20 token can maintain an allowance for a designated spender. The ERC-20 standard defines an approval function that authorizes a spender to use tokens up to an allowed amount, and an allowance function that reports the remaining permission.
Imagine a wallet with 500 units of a token. A user approves a swap contract to spend 100 units. The contract may then draw on that allowance to execute the authorized operation. An allowance is not the same as an immediate transfer: the tokens can remain in the wallet until the spender uses permission. The precise behavior depends on the token and the spender contract.
This is different from approving a blockchain transaction that transfers funds immediately. It is also different from allowing a website to display the wallet’s public address.
Why unlimited token allowances matter
Some applications request a very large allowance, sometimes effectively unlimited, so a user does not need to approve each future transaction. That can reduce repeated approval transactions and their network fees. It also increases the potential amount available to the spender if its authority is abused.
For example, a user approving only 50 tokens limits a conventional ERC-20 allowance to that amount. A user granting a virtually unlimited allowance may expose later deposits of that same token, provided the approval remains active. An exploit of the spending contract can therefore matter even if the initial swap has already finished.
An allowance does not grant access to every asset in a wallet. A permission for one ERC-20 token and one spender address generally does not authorize spending a different token. Other signing mechanisms, NFT operator approvals and malicious wallet signatures have separate rules and must be assessed separately.
How to inspect wallet permissions safely
- Start with the correct network. Identify whether the tokens and approvals exist on Ethereum, an Ethereum-compatible network or another chain. An allowance shown on one network does not automatically describe allowances on another.
- Use an established explorer or approval checker. Ethereum.org lists approval-review services in its official guide to revoking token access. Navigate from official documentation rather than a link in an unexpected message.
- Review the token, spender address and allowance. Confirm that the address actually belongs to the application you used. A familiar-looking name alone is insufficient.
- Prioritize unused, unfamiliar or excessive permissions. Consider the token balance today, the possibility of future deposits and the credibility of the spender.
- Check for other approval types. Some applications use signed permits or operator permissions that an ERC-20-only checker may not display.
You can often inspect public allowances without exposing a seed phrase or private key. Never enter recovery words into a permission-checking site. A tool requiring them is a serious warning sign.
How to revoke an approval
Revoking a conventional ERC-20 allowance usually means submitting a transaction that sets the authorized amount to zero. The network charges a fee to process the transaction, even though revocation itself is not a token sale.
Check the wallet popup for the correct network, token contract and spender before signing. Wait for transaction confirmation, then verify that the allowance has changed. Disconnecting a website session does not necessarily revoke an on-chain allowance.
Revoking may mean you need to approve the same spender again before using the application. It does not automatically close lending, staking or liquidity positions, so check the individual protocol’s withdrawal requirements before changing anything else.
What about signatures and permits?
Not every approval looks like a normal approval transaction. ERC-2612, for example, defines signed permits that can change allowances. Other authorization systems may have different scopes, deadlines and revocation mechanisms. A wallet prompt marked “sign” is therefore not automatically harmless just because it does not require an immediate network fee.
Review what the signature authorizes, who can submit it, any deadline and the relevant contract. If a message is opaque or pressures you to act immediately, decline it until the details can be independently checked.
A practical wallet-permission checklist
- Use official application URLs and verify the network before connecting.
- Prefer a narrow allowance when the interface supports it.
- Avoid signing unexpected permission requests or messages you cannot interpret.
- Check and remove approvals that are no longer needed.
- Keep higher-value long-term holdings away from experimental application activity where practical.
- Remember that revoking a permission does not recover assets already taken.
Frequently asked questions
Does disconnecting my wallet revoke an approval?
No. Disconnecting a website session and changing an on-chain token allowance are separate actions. Verify the allowance on the relevant network.
Will I lose tokens by revoking permission?
Revoking a conventional allowance does not itself transfer the token balance to a third party, although the revocation transaction may cost gas. Always confirm that your wallet shows the intended operation.
Can an approval remain active after a swap?
Yes. Many allowances remain until they are used up, replaced or revoked. Some newer authorization designs use time limits, so examine the specific permission rather than assuming all approvals expire.
Related BlockBriefing learning guides
Read what a crypto wallet is, compare hot and cold wallets, and review seed phrase security.
Primary sources and methodology
This guide explains common ERC-20 approval behavior, not every possible wallet permission. Original references: ERC-20 token specification, ERC-2612 permit specification and Ethereum.org’s revocation guide. No wallet, application or revocation tool is endorsed by this article.
Educational information only; not cybersecurity, legal or financial advice. Avoid approving transactions or signatures you do not understand.
