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ERC-20 Token Allowance Lookup (Vextorium)
x402
ERC-20 Token Allowance Lookup (Vextorium) is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-02).
Looks up how much of an ERC-20 token a spender is approved to transfer from an owner's wallet, and flags whether the approval is unlimited.
Price / call$0.003
Success—
StatusUnknown
How this service works
ERC-20 allowance lookup: how much a spender can move from an owner's balance, flagging unlimited approvals.
Output
Returns the approved allowance amount (as a number), a boolean flag indicating whether the approval is unlimited (max uint256), plus echoed fields for the network, token address, spender address, owner address, and an optional note field for additional context.
Example use cases
Audit unlimited DeFi approvals
“Check if the Aave v3 pool contract (0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2) has unlimited approval to spend my WETH (0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2) from my wallet 0xDead...Beef on Ethereum.”
Security review before token revoke
“Before I revoke approvals, can you tell me exactly how much DAI (0x6B175474E89094C44Da98b954EedeAC495271d0F) the 1inch router (0x1111111254EEB25477B68fb85Ed929f73A960582) is authorized to move from 0xMyWallet on Ethereum?”
Monitor spending permission on Base
“Look up the current allowance that the Base Uniswap v3 swap router has to spend USDC from wallet 0xAbc123... on the Base network, and flag if it's set to unlimited.”
Technical details
Endpoint
POSThttps://api.vextorium.com/permiso-token-pago?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a direct on-chain read of the ERC-20 allowance between a specific owner and spender pair — especially when you want automatic detection of unlimited approvals (max uint256). It supports five major EVM networks (Base, Ethereum, Arbitrum, Optimism, Polygon) in a single API, making it ideal for cross-chain wallet security audits, DeFi approval monitoring, or pre-transaction permission checks without needing your own RPC infrastructure.
Side effects
- Invalid or non-checksummed contract/wallet address returns an error
- Token address is not a valid ERC-20 contract on the specified network
- Network enum value not recognized (must be base, ethereum, arbitrum, optimism, or polygon)
- No allowance set (returns 0) which may be confused with an error
- RPC node timeout or network congestion causing a slow or failed read
- Missing required fields (token, propietario, gastador) causes validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"red": "base",
"nota": null,
"token": "USDC",
"permiso": 0,
"contrato": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"gastador": "0x3d4e44Eb1374240CE5F1B871ab261CD16335B76a",
"ilimitado": false,
"propietario": "0xb9f06D2734B7E9D7b21B64C4D8b95bd774b71aCf"
}
}Tags
x402
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