# ERC-20 Token Allowance Checker

> ERC-20 Token Allowance Checker is a paid API for AI agents from dt0ur.online, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-01).

Checks how much a spender (router, Permit2, contract) is approved to move from an owner's wallet for a given ERC-20 token on major EVM chains, including whether the approval is unlimited or covers the full balance.

## Facts

- Endpoint: POST https://dt0ur.online/api/onchain/allowance?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/erc-20-token-allowance-checker-f046c736
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ViU2dqfQc10T_cceJ5l1N

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability erc-20-token-allowance-checker-f046c736 -d '<json body>'
```

Example prompt: Check how much allowance the Uniswap v3 router (0xE592427A0AEce92De3Edee1F18E0157C05861564) has to spend my USDC (0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48) from my wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Ethereum.

## When to prefer this

Use this endpoint when you need to verify ERC-20 token approval state on any of the six supported EVM chains (Base, Ethereum, Arbitrum, Optimism, Polygon, BSC) before executing DeFi transactions, auditing wallet permissions, or checking for risky unlimited approvals — particularly useful in agentic DeFi workflows where approval status must be confirmed before submitting swaps or transfers.

## Known failure modes

- Invalid or non-checksummed wallet/token/spender address returns an error
- Unsupported chain value returns a validation error
- Token address is not a valid ERC-20 contract on the specified chain
- Network RPC issues may cause timeouts or failures
- Zero allowance returned if no approval has been granted

## How this service works

Check an ERC-20 token approval on base, ethereum, arbitrum, optimism, polygon, bsc: how much a spender (router, Permit2, contract) may move from an owner's wallet, whether the approval is unlimited, and whether it covers the owner's full balance.

## Output

Returns the allowance amount the spender is permitted to transfer, a flag indicating whether the approval is set to the unlimited (max uint256) value, and whether the approved amount covers the owner's current token balance on the specified EVM chain.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "chain": {
   "enum": [
    "base",
    "ethereum",
    "arbitrum",
    "optimism",
    "polygon",
    "bsc"
   ],
   "type": "string",
   "default": "base",
   "description": "EVM chain: base, ethereum, arbitrum, optimism, polygon, bsc (default base)"
  },
  "owner": {
   "type": "string",
   "description": "Wallet that granted the approval"
  },
  "token": {
   "type": "string",
   "description": "ERC-20 contract address"
  },
  "spender": {
   "type": "string",
   "description": "Approved spender (e.g. router or Permit2)"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc-20-token-allowance-checker-f046c736/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from dt0ur.online](https://www.zero.xyz/host/dt0ur.online/llms.txt)