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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).
Returns the current ERC-20 token allowance granted by an owner to a spender on Base, including risk assessment, balance, and revocation 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 it is unlimited, the owner's token balance, the spender's human-readable label (e.g. 'Uniswap Permit2'), a risk rating ('none', 'low', 'high'), an exposure value, a boolean revoke_recommended flag, an optional revoke_tx hex for on-chain revocation, token symbol and decimals, and the Base block number at query time.
Example use cases
Pre-trade approval safety check
“Before my swap, check if wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 has given Uniswap Permit2 (0x000000000022D473030F116dDEE9F6B43aC78BA3) unlimited USDC approval on Base, and whether that's risky.”
Revocation decision for stale approvals
“I want to clean up my wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 — check the USDC allowance it gave to 0x000000000022D473030F116dDEE9F6B43aC78BA3 on Base and tell me if you'd recommend revoking it.”
Agent portfolio risk monitoring
“As part of my onchain risk check, look up how much USDC token (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 has approved for spender 0x000000000022D473030F116dDEE9F6B43aC78BA3 on Base, and flag any unlimited exposure.”
Technical details
Endpoint
GEThttps://kr-x402-mvp.kgy5612.workers.dev/v1/allowance?utm_source=zero.xyzWhen to prefer
Use this endpoint when an AI agent needs to programmatically audit ERC-20 token approvals on Base without managing API keys — particularly for pre-trade safety checks, wallet security audits, or automated revocation workflows. Prefer this over block explorers when you need structured JSON with risk labels and revocation hints ready for agent consumption. The pay-per-call x402 model (0.002 USDC) makes it suitable for on-demand queries without subscription overhead.
Side effects
- Invalid owner or spender address format (must be 0x-prefixed 40-char hex) returns 400
- Unsupported token contract returns error or empty result
- Payment not included or insufficient USDC triggers x402 payment-required response
- RPC/network timeout on Base returns 503 or delayed response
- Non-Base token addresses silently default to USDC contract
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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