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ERC-20 Token Allowance Lookup (Ethereum)
x402
ERC-20 Token Allowance Lookup (Ethereum) is a paid API for AI agents from saylorinnovations.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-03).
Returns the current ERC-20 token allowance granted by a token owner to a spender on Ethereum mainnet
Price / call$0.002
Success—
StatusUnknown
How this service works
ERC-20 Allowance (ethereum). Ethereum ERC-20 allowance: how much a spender may move from an owner, human-readable, with an unlimited-approval flag.
Output
Returns the on-chain ERC-20 allowance value — the number of tokens (typically in the token's smallest unit) that the spender is permitted to transfer on behalf of the owner for the specified token contract on Ethereum mainnet.
Example use cases
DeFi protocol approval audit
“For the USDC token contract at 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48, check how many tokens my wallet 0xMyWallet... has approved the Uniswap v3 router at 0xE592427A0AEce92De3Edee1F18E0157C05861564 to spend on Ethereum.”
Security check for unknown approvals
“I want to verify whether address 0xSuspiciousSpender... has any spending allowance over my wallet 0xMyAddress... for the DAI token contract on Ethereum — can you look that up on-chain?”
Smart contract integration validation
“Before my dApp goes live, can you confirm the current allowance that owner 0xTestOwner... has granted to our new contract at 0xNewContract... for the WETH token at 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 on Ethereum mainnet?”
Technical details
Endpoint
GEThttps://saylorinnovations.com/api/evm/ethereum/allowance/:address/:address2/:address3?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to programmatically check ERC-20 spending allowances on Ethereum mainnet without running your own node or integrating a full blockchain SDK. Ideal for DeFi agents monitoring approvals, security tools auditing wallet permissions, or dApp workflows that need to verify allowances before initiating transfers.
Side effects
- Invalid Ethereum address format for any of the three address parameters returns an error
- Token contract address is not a valid ERC-20 contract (no allowance function) causes call failure
- Network congestion or RPC issues may cause timeouts
- Zero allowance returned when no approval has been set (valid response, not an error)
- Wrong address ordering (owner vs spender swapped) returns a valid but incorrect result silently
Tags
x402
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