What is a token approval, and how do you revoke one?

Before an app can swap your tokens, your wallet asks you to approve it. Approvals are normal and necessary, but old ones you forgot about are one of the ways wallets get drained.

What an approval is

An approval is a permission you give a smart contract to move a specific token from your wallet, up to an amount you set. It stays in place after the swap is done, until you change it.

Why they can be risky

• Unlimited approvals. Many apps ask for permission to move any amount, so you don't have to approve again next time. If that contract is ever exploited, everything you hold of that token is exposed.
• Forgotten approvals. Permissions you gave to apps you no longer use stay active.
• Signed permits. Some tokens allow approvals by signature instead of a transaction. That saves gas, but a phishing site can use the same kind of signature to take your tokens. Read what you are signing, and only sign on sites you opened yourself.

How to check your approvals

1. Go to revoke.cash (type the address yourself; fake copies exist), or to the Token Approvals page of the block explorer, such as Etherscan or Basescan.
2. Enter your wallet address or connect your wallet, and pick the network.
3. You see every token you approved, which contract can spend it, and how much.

How to revoke one

1. Find the approval you no longer need and click Revoke.
2. Confirm in your wallet. Revoking is a transaction, so it costs a small network fee.
3. Repeat on each network you use, because approvals are separate per network.

Good habits

• Approve only the amount you are about to swap when your wallet lets you edit it.
• Check your approvals every few months and revoke the ones you don't use.
• Keep long-term savings in a separate wallet that never connects to apps.

Nothing here is financial advice. Crypto transactions cannot be reversed.