# ERC20 Allowance Checker

> ERC20 Allowance Checker is a paid API for AI agents from apexfaucet.xyz, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-27).

Looks up the current ERC20 token allowance granted by an owner address to a spender contract on Ethereum, Base, Arc, or BNB Chain

## Facts

- Endpoint: GET https://apexfaucet.xyz/api/x402/evm-allowance?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-27
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/erc20-allowance-checker-41e49b46
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_NhTEY6R1HIZ-iNNlf7Os1

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 erc20-allowance-checker-41e49b46
```

Example prompt: Check the USDC allowance that wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 has granted to the Permit2 contract 0x000000000022D473030F116dDEE9F6B43aC78BA3 on Ethereum — tell me the exact amount and whether it's unlimited.

## When to prefer this

Use this endpoint when you need a quick, on-chain read of an ERC20 allowance across Ethereum, Base, Arc, or BNB Chain without running your own RPC node. It is ideal for pre-transaction checks, approval audits, and DeFi monitoring agents. At $0.001 per call it is cost-effective for single lookups; prefer a direct RPC call only if you already have an RPC node available and want to avoid per-call fees.

## Known failure modes

- Invalid Ethereum address format for token, owner, or spender (must match 0x + 40 hex chars)
- Unsupported chain value (only ethereum, base, arc, bnb accepted)
- Token contract does not exist on the specified chain
- RPC node unavailability or timeout causing lookup failure
- Payment failure — insufficient USDC balance for the $0.001 per-call fee

## How this service works

Free APEX on X1, and free USDC plus APEX on Arc, three times a day. No gas, no sign-up. Plus a swap, a screener, APEX City and token checks.

## Output

Returns a JSON object with ok (boolean), paid (amount charged), and a data object containing: allowance (human-readable amount), raw (raw on-chain value), symbol (token ticker), block (block number), blockTime (ISO timestamp of the block), chain, owner, token, spender addresses, and unlimited (boolean flag indicating max uint256 approval).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "queryParams"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "token",
      "owner",
      "spender"
     ],
     "properties": {
      "chain": {
       "enum": [
        "ethereum",
        "base",
        "arc",
        "bnb"
       ],
       "type": "string",
       "description": "Chain to read: ethereum, base, arc or bnb. Default ethereum."
      },
      "owner": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "Wallet that gave the approval."
      },
      "token": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "ERC20 token contract."
      },
      "spender": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "Contract allowed to spend."
      }
     }
    }
   }
  },
  "output": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "schema": {
  "type": "object",
  "properties": {
   "ok": {
    "type": "boolean"
   },
   "data": {
    "type": "object"
   },
   "paid": {
    "type": "number"
   }
  }
 },
 "example": {
  "ok": true,
  "data": {
   "ok": true,
   "raw": "0",
   "block": 26184816,
   "chain": "ethereum",
   "owner": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
   "token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
   "symbol": "USDC",
   "spender": "0x000000000022D473030F116dDEE9F6B43aC78BA3",
   "allowance": "0",
   "blockTime": "2026-10-13T16:38:35.000Z",
   "unlimited": false
  },
  "paid": 0.001
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc20-allowance-checker-41e49b46/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from apexfaucet.xyz](https://www.zero.xyz/host/apexfaucet.xyz/llms.txt)