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ERC-20 Allowance Lookup
x402
ERC-20 Allowance Lookup is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-02).
Returns how much a spender address is approved to transfer from an owner's ERC-20 token balance on a given EVM chain
Price / call$0.003
Success—
StatusUnknown
How this service works
How much a spender is approved to move from an owner — Genesis402 / UnyKorn Operator Network
Output
Returns a JSON object with ok status, the allowance type identifier, and a receipt containing a transaction hash, the USD cost of the call ($0.003), and a unique receipt ID — confirming how many tokens the spender is approved to move from the owner for the given ERC-20 contract on the specified chain.
Example use cases
Pre-swap approval check on a DEX
“Before I do a swap on Arbitrum, can you check whether the SushiSwap router (0x1b02dA8Cb0d097eB8D57A175b88c7D8b47997506) has enough allowance to spend my WETH (0x82aF49447D8a07e3bd95BD0d56f35241523fBab1) from my wallet (0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B)?”
DeFi lending protocol approval audit
“I want to know how much the Aave v3 pool contract (0x794a61358D6845594F94dc1DB02A252b5b4814aD) is allowed to move from my address (0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B) for USDC (0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174) on Polygon.”
Security check for unknown approval
“I think I may have approved a suspicious contract (0xDeadBeef12345678901234567890123456789012) to spend my DAI (0x6B175474E89094C44Da98b954EedeAC495271d0F) on Ethereum — can you look up the current allowance from my wallet (0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B) to that address?”
Technical details
Endpoint
POSThttps://twin.unykorn.org/erc20-allowance?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to programmatically check the current ERC-20 spending allowance between two specific addresses on any of 10 supported EVM chains without running your own node. It is ideal for pre-transaction approval validation, DeFi workflow automation, and security auditing of token approvals. It is preferable when you need a pay-per-call, no-subscription approach via the x402 protocol.
Side effects
- Invalid Ethereum address format for owner, spender, or contract (must be 0x + 40 hex chars)
- Unsupported chain name — only ethereum, base, polygon, arbitrum, optimism, bsc, avalanche, gnosis, linea, scroll are accepted
- RPC node unavailable for the requested chain
- Payment failure via x402 protocol (insufficient USDC balance)
- Contract address is not a valid ERC-20 token
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| params | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"type": "erc20-allowance",
"receipt": {
"tx_hash": "0x<64hex>",
"amount_usd": 0.003,
"receipt_id": "g402-<16hex>"
},
"generated_at": "<iso8601>"
}
}Tags
x402
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