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ERC20 Allowance Lookup (eth_call)
x402
ERC20 Allowance Lookup (eth_call) is a paid API for AI agents from skills.onesource.io, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-13).
Returns the current ERC20 token allowance — how many tokens a spender is approved to transfer from an owner's wallet — via live eth_call on supported networks.
Price / call$0.003
Success—
StatusUnknown
How this service works
ERC20 allowance via allowance (eth_call) - how much a spender is approved to move from an owner's wallet
Output
Returns a JSON object with the allowance amount (as a string), token metadata (name, symbol, decimals), and the owner, spender, and token addresses. The allowance is in raw token units (apply decimals to get human-readable amount).
Example use cases
Audit DeFi protocol spending limits
“I need to check how much USDC the Uniswap V3 router is approved to spend from my wallet on Ethereum. Can you look up the current allowance for me?”
Verify token approvals before swap
“Before I execute a swap, show me how many tokens the 1inch router has been approved to transfer from my address on Base network. The token is at 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.”
Detect unlimited approvals in wallet
“I want to audit my wallet for risky token approvals. Can you check if I've given any DeFi contracts unlimited allowance for my tokens? Start by checking my USDT approval on Ethereum.”
Technical details
Endpoint
GEThttps://skills.onesource.io/api/chain/allowanceWhen to prefer
Use this endpoint when you need to read a live ERC20 allowance directly from the chain via eth_call, including token metadata like name, symbol, and decimals in one response. Prefer this over generic RPC tools when you want structured JSON output with token context across multiple networks (Ethereum, Base, Avalanche, Sepolia, MegaETH).
Side effects
- Invalid Ethereum address format for owner, spender, or token returns a validation error
- Unsupported network value returns an enum validation error
- Token address is not an ERC20 contract — eth_call returns empty or reverts
- Network RPC is temporarily unavailable — returns a 5xx error
- Zero allowance returned when no approval has been set (not an error, valid response)
Input
{
"owner": "0x1234567890123456789012345678901234567890",
"token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
"network": "ethereum",
"spender": "0x0987654321098765432109876543210987654321"
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| owner | string | |
| token | string | |
| network | string | |
| spender | string |
Output
{
"data": {
"name": "USD Coin",
"owner": "0x1234567890123456789012345678901234567890",
"token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
"symbol": "USDC",
"spender": "0x0987654321098765432109876543210987654321",
"decimals": 6,
"allowance": "0"
},
"meta": {
"endpoint": "/api/chain/allowance",
"request_id": "668fc1cf5e608fb4"
}
}Schema · Response
| Field | Type | Description |
|---|---|---|
| datarequired | object | |
| metarequired | object |
Tags
x402
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