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Ethereum ERC-20 Allowance Lookup
x402
Ethereum ERC-20 Allowance Lookup is a paid API for AI agents from api.arysphere.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-17).
Returns the raw ERC-20 token allowance a holder (owner) has granted to a spender on Ethereum mainnet.
Price / call$0.002
Success—
StatusUnknown
How this service works
ARYSPHERE sells AI-written verdicts on Base token contracts (a grade, a one-liner, a roast and the contract's facts) and Base/Ethereum chain reads, paid per call in USDC on Base over x402 v2. No account and no API key.
Output
A JSON object containing a boolean 'ok' field, the chain identifier, the method used, the service name, and most importantly 'result' — the uint256 allowance as a decimal string representing the raw token units approved by the owner for the spender. On failure, an 'error' field is included instead.
Example use cases
Pre-trade DeFi approval check
“Before I swap on Uniswap, check whether my wallet 0xAbCd...1234 has already approved the Uniswap v2 router 0x7a25...5678 to spend my USDC at contract 0xA0b8...eB48 on Ethereum mainnet, and tell me the approved amount.”
Security audit of token approvals
“I want to audit my token approvals — can you check how much of the DAI token at 0x6B17...1d0F I've approved for the Aave lending pool 0x7d25...9999 from my wallet 0xDEaD...bEEf on Ethereum mainnet?”
Smart contract pre-flight validation
“Before executing the batch transfer in my smart contract, verify that the spender contract at 0xC02a...aC42 has been granted enough allowance by owner 0xBEEF...0001 on the WETH token at 0xC02a...aC42 on Ethereum mainnet.”
Technical details
Endpoint
GEThttps://api.arysphere.com/v1/ventures/x402_eth_reads_v1/eth_mainnet_erc20_allowance?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to read the current ERC-20 allowance on Ethereum mainnet for a specific owner-spender-token triple without writing any transaction. It is ideal for pre-trade checks, approval auditing, and DeFi automation flows where you need the raw uint256 value directly from the contract. Prefer this over general blockchain RPC calls when you want a simple, pay-per-use HTTP GET with no node infrastructure setup required.
Side effects
- Invalid address format (owner, token, or spender not matching 0x + 40 hex pattern) returns validation error
- Token contract address is not a valid ERC-20 contract, causing a revert or zero return
- Ethereum node unavailability or RPC timeout causes failure
- Missing required query parameters (token, owner, spender) results in bad request error
- Payment failure (insufficient USDC balance or x402 protocol error) blocks the request
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"chain": "ethereum",
"method": "allowance",
"result": "0",
"service": "x402_eth_reads_v1.eth_mainnet_erc20_allowance"
}
}Tags
x402
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