Revoke Allowances
Security Guide

如何撤销智能合约授权(保持安全)

Protect your crypto by removing dangerous token approvals. Essential security for every DeFi user.

10 min read
Updated: January 2026

Why This Matters

Over $2 billion has been stolen through exploited token approvals. If you have ever used a DEX, bridge, or DeFi protocol, you likely have active approvals that could put your funds at risk.

What Are Token Allowances?

When you interact with DeFi protocols, you must grant them permission to move your tokens. This permission is called an allowance or approval.

How It Works

  1. 1You want to swap USDC for ETH on Uniswap
  2. 2Uniswap asks for approval to access your USDC
  3. 3You sign an approval transaction
  4. 4Uniswap can now move your USDC for swaps

The Problem

Most protocols request UNLIMITED approvals for convenience. This means:

  • The contract can drain ALL your tokens
  • Approval persists forever until revoked
  • If hacked, attackers get full access
  • Most users forget about old approvals

Why Unlimited Allowances Are Dangerous

Not all approvals carry the same risk. Here is how to assess your exposure.

critical

Unlimited Approval

Contract can spend infinite tokens

Approve MAX_UINT256 (unlimited) to Uniswap
high

Large Amount Approval

High value approval to less-known contracts

Approve 10,000 USDT to unknown DEX
medium

Old Unused Approval

Approval to contracts you no longer use

Approval from 2 years ago to defunct project
low

Trusted Protocol Approval

Limited approval to verified protocols

Approve 100 USDC to Aave

How to Check Your Allowances

Use these trusted tools to view and manage your token approvals.

Recommended
R

Revoke.cash

100+ chains

  • Free to use
  • Multi-chain support
  • Batch revocations
  • Browser extension
Visit Tool
Recommended
E

Etherscan Token Approval

Ethereum + L2s chains

  • Official tool
  • Detailed history
  • ERC-20/721/1155
  • Transaction details
Visit Tool
U

Unrekt.net

10+ chains

  • Simple interface
  • Quick check
  • Popular chains
  • Mobile friendly
Visit Tool
Recommended
R

Rabby Wallet

50+ chains

  • Built-in wallet
  • Pre-sign check
  • Risk alerts
  • Auto detection
Visit Tool

Step-by-Step Revocation Guide

Choose your preferred tool and follow the steps to revoke dangerous approvals.

1

Visit Revoke.cash

Go to the official website

  • Navigate to revoke.cash in your browser
  • Ensure you are on the official site (check URL)
  • The site works without connecting wallet initially
2

Connect Your Wallet

Link MetaMask or other wallet

  • Click "Connect Wallet" button
  • Select your wallet provider (MetaMask, WalletConnect, etc.)
  • Approve the connection request
3

Select Network

Choose the blockchain to check

  • Click the network selector dropdown
  • Choose Ethereum, Polygon, Arbitrum, or other chain
  • Repeat for each network you have used
4

Review Allowances

Check all active approvals

  • Wait for the page to load all approvals
  • Sort by value at risk or date
  • Identify unlimited or suspicious approvals
5

Revoke Unwanted Approvals

Remove risky permissions

  • Click "Revoke" next to each unwanted approval
  • Confirm the transaction in your wallet
  • Pay the gas fee to complete revocation
6

Verify Revocation

Confirm approval is removed

  • Wait for transaction confirmation
  • Refresh the page to verify removal
  • The approval should no longer appear in the list

Gas Costs Explained

Revoking approvals costs gas. Here are estimated costs per network.

Ethereum

$2-15

1-5 min

Polygon

$0.01-0.05

< 30 sec

Arbitrum

$0.10-0.50

< 1 min

Optimism

$0.05-0.30

< 1 min

BSC

$0.05-0.20

< 30 sec

Base

$0.01-0.10

< 1 min

Pro Tip: Save on Gas

Revoke approvals during weekends or early morning UTC when gas prices are typically 30-50% lower. Use gas trackers like Etherscan Gas Tracker to find the best times.

When to Revoke Allowances

Know when to take action to protect your assets.

High

After using a new DeFi protocol

New protocols carry higher risk of exploits

High

When you stop using a protocol

No need to maintain exposure to unused contracts

Medium

After interacting with NFT mints

NFT contracts often request broad approvals

Medium

Monthly security audit

Regular maintenance prevents forgotten risks

Critical

After news of protocol hack

Immediate action needed if you used the protocol

Low

Before large token transfers

Clean slate before moving significant funds

Best Practices for Token Approvals

Follow these guidelines to minimize your risk exposure.

Use Exact Amounts

Only approve the exact amount needed for a transaction, not unlimited.

Check Before Signing

Always read approval requests carefully. Use wallets like Rabby that show risk warnings.

Regular Audits

Check your approvals monthly. Set a calendar reminder for regular reviews.

Use Separate Wallets

Keep main holdings in a cold wallet. Use hot wallets for DeFi with limited funds.

Verify Contracts

Only interact with verified contracts. Check if the contract is audited.

Revoke After Use

Immediately revoke approvals after finishing with a protocol, especially new ones.

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Frequently Asked Questions

Common questions about token allowances and revocation.