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ERC-20 Allowance Checker
Learn about token approvals and understand allowance risks
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Educational Tool
This tool helps you understand ERC-20 token allowances and their risks. It does not connect to any wallet or blockchain.
What are Token Allowances?
When you interact with DeFi protocols (like Uniswap, Aave, etc.), you often need to approve them to spend your tokens. This is called setting an allowance.
The Approval Flow:
- You call
approve(spender, amount)on the token contract - This allows the spender to transfer up to
amountof your tokens - The spender can then call
transferFrom()to move your tokens
Common Risks:
- Unlimited Approvals: Many dApps request max approval (2^256 - 1)
- Forgotten Approvals: Old approvals remain active even after you stop using a protocol
- Malicious Contracts: Scam sites can drain your tokens if you approve them
Analyze an Allowance
Enter the raw allowance value (paste from Etherscan or use common values below)
Common values:
Best Practices
- • Only approve the exact amount you need for a transaction
- • Revoke allowances for protocols you no longer use
- • Use tools like Revoke.cash to manage your allowances
- • Be extra cautious with unlimited approvals
- • Verify contract addresses before approving
About ERC-20 Allowance Checker
What is ERC-20 Allowance Checker?
Understand ERC-20 token allowances and their security implications. Learn about unlimited approvals, revocation, and best practices for protecting your tokens from exploits.
Features & Benefits
- Allowance security education
- Approval risk explanation
- Revocation guidance
- Best practices overview
- Common exploit awareness
- Wallet security tips
Frequently Asked Questions
- What is a token allowance?
- Permission you grant to a smart contract to spend your tokens. 'Approve' transactions set this allowance amount.
- Why are unlimited approvals risky?
- If the approved contract is exploited or malicious, attackers can drain all your tokens—not just what you intended to use.
- How do I revoke allowances?
- Use tools like Revoke.cash or Etherscan's token approval checker. You'll pay gas to set allowance to 0.
Related Tools
How-To Guides
100% Private & Secure
This tool runs entirely in your browser. Your files and data never leave your device and are not uploaded to any server.