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ERC-20 Token Allowance Checker (Base Chain)
x402
ERC-20 Token Allowance Checker (Base Chain) is a paid API for AI agents from kr-x402-mvp.kgy5612.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-31).
Fetches the current ERC-20 token allowance granted by an owner to a spender on Base, including balance, exposure risk, and revoke recommendation.
Price / call$0.002
Success—
StatusUnknown
How this service works
Pay-per-call crypto microdata for trading/onchain AI agents via x402 (USDC on Base): Base gas, token risk, balances, multi-venue prices, Hyperliquid book/funding, kimchi premium. No API keys.
Output
Returns a JSON object with the current allowance (human-readable and raw), whether the allowance is unlimited, the owner's token balance, the spender's known label (e.g. 'Uniswap Permit2'), a risk classification, the exposure amount, and a boolean revoke_recommended flag plus a revoke_tx if applicable. Also includes chain context (block number, chain name, token symbol, decimals).
Example use cases
Pre-swap approval audit
“Before I swap on Uniswap, check whether my wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 has already approved the Permit2 router 0x000000000022D473030F116dDEE9F6B43aC78BA3 to spend my USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, and whether that allowance is safe or unlimited.”
Security sweep for unlimited approvals
“Audit wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 — check if the USDC allowance granted to spender 0x000000000022D473030F116dDEE9F6B43aC78BA3 on Base is unlimited and whether I should revoke it.”
Agent self-check before paying counterparty
“My agent is about to pay 1 USDC to 0x000000000022D473030F116dDEE9F6B43aC78BA3 from 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 on Base — quickly check the current USDC allowance and whether the spender is already authorized for at least that amount.”
Technical details
Endpoint
GEThttps://kr-x402-mvp.kgy5612.workers.dev/api/chain/allowance?utm_source=zero.xyzWhen to prefer
Use this endpoint when an AI agent needs to verify on-chain ERC-20 token approvals on Base before executing a DeFi transaction, auditing wallet security, or checking whether a spender (e.g. a DEX router) already has sufficient allowance. Prefer it over general blockchain explorers when you need structured, machine-readable allowance data with risk classification and revoke recommendations in a single low-cost call. Requires no API key — pay $0.002 USDC per call via x402.
Side effects
- Invalid Ethereum address format for owner or spender returns a validation error
- Token contract address not found on Base returns an error or empty result
- Network or RPC timeout may return a 503 or empty response
- Wallet with zero balance or no prior approval returns allowance of 0 and revoke_recommended false
- Missing required owner or spender query params returns 400 bad request
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"risk": "none",
"block": 53250000,
"chain": "base",
"owner": "0xe4be4d0bd82d8e68203deff81f79ede0529f2617",
"token": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"symbol": "USDC",
"spender": "0x000000000022D473030F116dDEE9F6B43aC78BA3",
"decimals": 6,
"exposure": 0,
"allowance": 0,
"revoke_tx": null,
"unlimited": false,
"allowance_raw": "0",
"owner_balance": 0.079,
"spender_label": "Uniswap Permit2",
"revoke_recommended": false
}
}Tags
x402
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