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Aether Base Token Allowance Lookup
x402
Aether Base Token Allowance Lookup is a paid API for AI agents from aether-x402.vercel.app, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-12).
Queries the ERC-20 token spending allowance granted by an owner address to a spender address on Base mainnet.
Price / call$0.002
Success—
StatusUnknown
How this service works
Pay-per-call Base onchain data, token risk verdicts and x402 payability audits over x402 (USDC on Base).
Output
Returns a JSON object with three fields: 'raw' (the allowance as a raw integer string), 'formatted' (human-readable decimal amount), and 'unlimited' (boolean indicating whether the allowance is set to the maximum uint256 value, i.e. effectively unlimited).
Example use cases
DeFi approval security audit
“I want to check how much allowance my wallet 0x1234...abcd has granted to the Uniswap router contract 0x2626...6200 for the USDC token 0x8338...4820 on Base — is it set to unlimited?”
Pre-trade allowance verification
“Before my agent executes a swap, check whether address 0xabc1...2345 has enough spending allowance set for contract 0xdef6...7890 on token 0x4200...0006 on Base so we know if an approval transaction is needed first.”
Allowance monitoring for suspicious grants
“Check the current token allowance that wallet 0x9876...fedc has approved for the contract 0x1111...aaaa on the WETH token 0x4200...0006 on Base — I'm auditing this wallet for overly permissive approvals.”
Technical details
Endpoint
POSThttps://aether-x402.vercel.app/v1/base/allowance?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a fast, pay-per-call lookup of ERC-20 token allowances on Base mainnet without setting up your own RPC infrastructure. It is ideal for AI agents that need to check approval state before executing DeFi operations, audit wallets for risky unlimited approvals, or verify spending permissions programmatically using USDC micropayments via the x402 protocol.
Side effects
- Invalid Ethereum address format for owner, token, or spender returns a validation error
- Token contract address is not a valid ERC-20 contract on Base, resulting in a call failure or zero response
- Payment via x402/USDC fails if the calling agent lacks sufficient USDC balance on Base
- Rate limiting or service unavailability from the underlying Base RPC node
- Spender or owner address that has never interacted returns allowance of 0 (not an error, but may be misread as failure)
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| owner | string | |
| token | string | |
| spender | string |
Output
Schema · Response
{
"type": "json",
"example": {
"raw": "0",
"formatted": "0",
"unlimited": false
}
}Tags
x402
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