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ERC20 Allowance Checker
x402
ERC20 Allowance Checker is a paid API for AI agents from flat-rate-llm.kikoribera03.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-29).
Returns how many tokens a spender is approved to transfer on an ERC20 owner's behalf, including whether the approval is effectively unlimited.
Price / call$0.005
Success—
StatusUnknown
How this service works
How much of a token a spender is still allowed to move on an owner's behalf, and whether that approval is unlimited. The check to run before an approve, and the one that finds forgotten infinite approvals. Via eth_call (allowance).
Output
Returns an object with: raw (raw big-integer allowance as a string), amount (human-readable decimal amount adjusted for token decimals), decimals (the token's decimal precision), and unlimited (boolean flag indicating whether the approval is effectively infinite, i.e. max uint256).
Example use cases
Audit forgotten infinite approvals
“Check if I ever gave unlimited approval to the Aave lending pool (0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2) to spend my WETH (0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2) — my wallet is 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Ethereum mainnet.”
Pre-approve transfer check
“Before I call approve, can you tell me the current allowance the 1inch router (0x1111111254EEB25477B68fb85Ed929f73A960582) has to spend my USDC (0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48) from address 0xAbCd1234...5678 on Ethereum?”
DeFi security monitoring
“I want to know if any unlimited approvals are set for the SushiSwap router (0xd9e1cE17f2641f24aE83637ab66a2cca9C378B9F) on my Polygon wallet 0x1234abcd...ef56 for the MATIC token at 0x7D1AfA7B718fb893dB30A3aBc0Cfc608AaCfeBB0.”
Technical details
Endpoint
GEThttps://flat-rate-llm.kikoribera03.workers.dev/v1/evm/erc20-allowance?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a quick, read-only ERC20 allowance lookup without setting up your own RPC connection or Web3 library. It is ideal for agents performing DeFi safety checks, pre-flight approval validation before a swap or transfer, or auditing wallets for forgotten infinite approvals. Prefer this over raw eth_call endpoints when you want decimals-adjusted human-readable output and the unlimited flag already computed.
Side effects
- Invalid or non-checksummed Ethereum address returns an error
- Unsupported chain name returns a validation error
- Non-ERC20 contract address (e.g. EOA or non-standard contract) may return zero or error
- Network congestion or RPC errors may cause timeouts
- Token contract with no allowance function returns an error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| chain | string | base | ethereum | polygon | arbitrum | optimism. |
| ownerrequired | string | Address that owns the tokens. |
| tokenrequired | string | ERC20 contract address. |
| spenderrequired | string | Address allowed to spend them. |
Output
Schema · Response
| Field | Type | Description |
|---|---|---|
| raw | string | |
| amount | number | |
| decimals | number | |
| unlimited | boolean |
Tags
x402
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