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Token Allowance & Balance Pre-flight Check
x402
Token Allowance & Balance Pre-flight Check is a paid API for AI agents from api.eucompliance.tools, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).
Returns ERC-20 token allowance, balance, decimals, and symbol in one call, with an optional would_succeed verdict for a proposed transfer amount on Base, Ethereum, Arbitrum, Optimism, or Polygon.
Price / call$0.002
Success—
StatusUnknown
How this service works
Pre-flight check before a swap or transfer: ERC-20 allowance, balance, decimals and symbol in one call, read live from the chain at the latest block. Pass an amount and get a straight would_succeed verdict with the blocking reason and the action needed. Base, Ethereum, Arbitrum, Optimism, Polygon. A missing approval burns the gas of a failed transaction - this call costs a fraction of that.
Output
Returns the token's balance, allowance, decimals, and symbol read live from the chain at the latest block. If an amount and spender are provided, also returns a boolean would_succeed verdict, the specific blocking reason (e.g. insufficient balance or missing approval), and the action required to fix it (e.g. approve spender or acquire more tokens).
Example use cases
Pre-swap approval check on Base
“I'm about to swap 1000 USDC on Base using Uniswap's router 0x2626664c2603336E57B271c5C0b26F421741e481 from my wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 — can you check if my allowance and balance are sufficient and tell me if the swap would go through?”
Diagnose failed token transfer on Polygon
“My WMATIC transfer on Polygon keeps failing — can you check the balance and allowance for token 0x0d500B1d8E8eF31E21C99d1Db9A6444d3ADf1270, owned by 0xAbCd...5678, to see what's blocking it?”
Batch pre-flight before multi-chain DeFi bot
“Before my bot executes, check the USDT token 0xdAC17F958D2ee523a2206206994597C13D831ec7 on Ethereum: wallet 0x742d35Cc6634C0532925a3b844Bc454e4438f44e, spender 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D, amount 5000 — would it succeed, and what action do I need to take?”
Technical details
Endpoint
GEThttps://api.eucompliance.tools/x402/tokenWhen to prefer
Choose this endpoint when you need to verify ERC-20 token state before executing a swap, transfer, or DeFi interaction and want to avoid wasting gas on a predictably failing transaction. It consolidates balance, allowance, decimals, and symbol into a single read call and adds an actionable verdict, making it ideal for any agent or bot that needs to pre-validate token conditions on Base, Ethereum, Arbitrum, Optimism, or Polygon before submitting a transaction.
Side effects
- Invalid or non-ERC-20 contract address returns an error or zero values
- Unsupported chain value returns a validation error
- Owner or spender address malformed returns a parameter error
- Network RPC timeout causes a delayed or failed response
- Amount specified without spender omits the would_succeed verdict
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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