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ERC-20 Token Allowance Lookup
x402
ERC-20 Token Allowance Lookup is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-19).
Returns how many tokens a spender is approved to move from an owner's wallet on a given EVM network, flagging whether the approval is unlimited.
Price / call$0.003
Success—
StatusUnknown
How this service works
558 pay-per-call data APIs for AI agents: Solana and EVM on-chain data, tokenized stocks, DeFi, Hyperliquid, economy and official statistics, FX, validation, web and developer tools. Pay in USDC via x402.
Output
Returns a JSON object with the token symbol, contract address, network, owner and spender addresses, the numeric allowance (permission), and a boolean 'unlimited' flag indicating whether the approval is set to the maximum uint256 value. Also includes an optional note field.
Example use cases
Wallet security audit for risky approvals
“Scan my wallet 0xb9f06D2734B7E9D7b21B64C4D8b95bd774b71aCf on Ethereum — check whether the Uniswap router 0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45 has an unlimited approval on my USDC tokens.”
Pre-transaction allowance verification
“Before I submit a swap on Arbitrum, check if contract 0x1b02dA8Cb0d097eB8D57A175b88c7D8b47997506 already has enough WETH allowance from my wallet 0xabc123...def456 to cover a 2 WETH trade.”
DeFi protocol approval monitoring
“I want to know how much DAI the Aave lending pool contract 0x794a61358D6845594F94dc1DB02A252b5b4814aD is allowed to move from wallet 0xdef789...abc012 on Polygon — flag it if it's set to unlimited.”
Technical details
Endpoint
POSThttps://api.vextorium.com/v1/token-allowance?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a fast, single on-chain read of an ERC-20 allowance without running your own blockchain node or writing contract call code. It is ideal for wallet security dashboards, pre-swap checks, and approval auditing workflows across Base, Ethereum, Arbitrum, Optimism, and Polygon. Prefer this over general-purpose blockchain RPC tools when you specifically need the allowance amount and an explicit unlimited-approval flag in a structured JSON response.
Side effects
- Invalid or malformed wallet/contract addresses return an error
- Unsupported network returns a validation error
- Token contract address not found on the specified network may return null values
- RPC node timeout causes a failed lookup
- Missing required fields (token, owner, spender) returns a schema validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| owner | string | Owner wallet address |
| token | string | Token contract address |
| network | string | EVM network (default base) |
| spender | string | Spender (contract) address |
Output
Schema · Response
{
"type": "json",
"example": {
"note": null,
"owner": "0xb9f06D2734B7E9D7b21B64C4D8b95bd774b71aCf",
"token": "USDC",
"network": "base",
"spender": "0x3d4e44Eb1374240CE5F1B871ab261CD16335B76a",
"contract": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"unlimited": false,
"permission": 0
}
}Tags
x402
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