Unlimited Approval
An unlimited approval is a token permission that lets a smart contract move any amount of a specific token from your wallet, with no upper limit and no expiry. It saves fees and clicks, but it leaves your whole balance of that token exposed if the contract is ever abused.
What unlimited actually means
When you use a decentralized app, you first approve it to spend a token on your behalf. The approval contains a number, the allowance. Many apps request the largest number the token standard can store, a value so huge that it works as infinite. In your wallet this often appears as unlimited or as a very long number.
The approval covers one token on one address, not your whole wallet. But it covers all of that token you hold now and everything of that token you receive later, until you revoke it.
Why apps ask for it
Each approval is a separate on-chain transaction with its own fee. If you trade on the same exchange every week, approving the exact amount each time means paying twice and confirming twice. An unlimited approval removes that friction, which is why it became the default in much of DeFi.
An example of how it goes wrong
Say two years ago you gave a yield app unlimited approval for USDC and deposited 500 USDC. You withdrew long ago and forgot about it. Today your wallet holds 20,000 USDC. If that app's contract is hacked, or if its operators turn malicious, the forgotten approval lets the contract pull all 20,000, not just the original 500.
This is not theoretical. Bugs in approved contracts and compromised website front ends have repeatedly let attackers drain tokens from users who had approved them. In December 2021, for example, a malicious script injected into the BadgerDAO website prompted users to approve an attacker's address, and funds were later taken through those approvals.
Safer habits
Where your wallet allows it, edit the requested amount to what you actually plan to use, a so-called spending cap. Prefer exact approvals for apps you use once. Keep larger holdings in a wallet that does not interact with DeFi. Review your approvals with a token approval checker on a block explorer every few months and revoke the ones you no longer use, especially for old or little-known contracts.
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Frequently asked questions
Is an unlimited approval always dangerous?
Not by itself. It is only as safe as the contract you approved. A well-audited, widely used contract is lower risk than an unknown one, but no contract is risk-free and the exposure lasts until you revoke.
Does an unlimited approval give access to all my coins?
No. It applies to one specific token. However, you may have given separate unlimited approvals for many tokens over time, which together can cover most of your wallet.
How do I remove an unlimited approval?
Use a token approval checker on a block explorer or a revoke tool, connect your wallet, and send a revoke transaction that sets the allowance to zero. It costs a small network fee.
Related terms
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