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ERC-20 Token Allowance Lookup
x402
ERC-20 Token Allowance Lookup is a paid API for AI agents from biosfera.46-62-215-147.sslip.io, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).
Returns the amount of an ERC-20 token a spender is approved to transfer on behalf of an owner, in both raw units and decimal value, across major EVM chains.
Price / call$0.001
Success—
StatusUnknown
How this service works
Use when you need how much of an ERC-20 token a spender is approved to move from an owner, on Base, Ethereum, Arbitrum, Optimism or Polygon, via allowance(owner, spender). Returns raw units and decimal value.
Output
Returns the approved allowance amount in raw token units (e.g. wei-equivalent integers) and as a human-readable decimal value adjusted for the token's decimals, along with metadata such as token symbol and decimal precision.
Example use cases
DeFi approval safety audit
“Check how much WETH the Aave lending pool at 0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2 is approved to spend from my wallet 0xDeAd...bEeF on Ethereum — I want to make sure I haven't given it an unlimited approval.”
DEX router allowance check
“Before I submit a swap, can you look up the current USDC allowance that the Uniswap v3 router 0xE592427A0AEce92De3Edee1F18E0157C05861564 has on behalf of 0x1234...abcd on Base?”
Token approval monitoring for a vault
“Check the DAI allowance on Polygon for spender 0x794a61358D6845594F94dc1DB02A252b5b4814aD from owner 0xABCD...7890 — I need to know if the Aave vault is still authorized to pull funds.”
Technical details
Endpoint
GEThttps://biosfera.46-62-215-147.sslip.io/o/erc20-allowance?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to check on-chain ERC-20 token approvals across Base, Ethereum, Arbitrum, Optimism, or Polygon without running your own RPC node. It's ideal for DeFi agents that need to verify spending permissions before executing swaps, transfers, or vault interactions, or for monitoring and auditing token approvals granted to third-party contracts.
Side effects
- Invalid Ethereum address format for owner, spender, or token returns a 400 error
- Unsupported chain name returns a validation error
- Token address that is not a valid ERC-20 contract may return zero or a contract call error
- RPC node timeout or chain congestion may cause slow or failed responses
- Zero allowance returned when spender has not been approved — not an error, but may be misread as a failure
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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