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ERC-20 Token Allowance Lookup
x402
ERC-20 Token Allowance Lookup is a paid API for AI agents from x402-agent-store.rileycraig14.workers.dev, paid per call via x402, $0.09/call, status unknown (last checked 2026-09-13).
Returns the current ERC-20 token spending allowance approved by an owner address for a specific spender on a given chain
Price / call$0.09
Success—
StatusUnknown
How this service works
How much of an ERC-20 token a spender is approved to move from an owner's wallet, via allowance, across Base, Ethereum, Optimism, Arbitrum, Polygon, Gnosis. The approval read every DeFi, swap and trading agent makes before (and after) a transaction to know if an approve is needed. Live public RPC; one paid call at $0.001.
Output
A JSON object containing the blockchain network, owner address, token contract address, spender address, token decimals, the human-readable allowance as a number, and the raw allowance as a string in the token's base units (e.g. wei for 18-decimal tokens, micro-units for USDC).
Example use cases
Example prompt
“What's the current USDC allowance that my wallet 0xAbC...123 has approved for the Uniswap router 0xDef...456 on Base? Use the token contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48.”
Technical details
Endpoint
GEThttps://x402-agent-store.rileycraig14.workers.dev/chain/allowanceWhen to prefer
Use this endpoint when you need a single, on-demand allowance check for a specific owner/spender/token triple on EVM-compatible chains (Base, Ethereum, Optimism, Arbitrum, Polygon, Gnosis) without needing an API key. Prefer this over ethers.js or web3 direct calls when operating in a serverless or agent context that benefits from HTTP-based on-chain reads with micropayment billing.
Side effects
- Invalid or non-checksummed address formats return an error
- Unsupported chain identifier returns a validation error
- Token contract address is not a valid ERC-20 contract — returns error or zero allowance
- RPC node unavailability causes timeout or 5xx response
- Missing required query parameters (token, owner, spender) return 400 bad request
- Payment not included or insufficient — returns 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"chain": "base",
"owner": "0x...",
"token": "0x...",
"spender": "0x...",
"decimals": 6,
"allowance": 1000,
"raw_allowance": "1000000000"
}
}Tags
x402
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