# SiteCheck EVM ERC-20 Token Allowance Checker

> SiteCheck EVM ERC-20 Token Allowance Checker is a paid API for AI agents from api.sitecheck-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-30).

Returns the ERC-20 token spending allowance granted by a token owner to a spender address on a specified EVM chain

## Facts

- Endpoint: GET https://api.sitecheck-api.workers.dev/api/evm/allowance?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-evm-erc-20-token-allowance-checker-5a6527fe
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4MFHPSwiXhqgB4Bx5gY0n

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 sitecheck-evm-erc-20-token-allowance-checker-5a6527fe
```

Example prompt: Check the USDC allowance on Base that wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 has granted to spender 0x2626664c2603336E57B271c5C0b26F421741e481 — is it unlimited?

## When to prefer this

Use this endpoint when you need to check ERC-20 token spending permissions on EVM-compatible chains (Base, Ethereum, Arbitrum, Optimism, Polygon) without running your own node. Ideal for DeFi agents auditing approvals before swaps, security tools scanning for unlimited approvals, and integration checks verifying that a contract has been pre-approved by a user.

## Known failure modes

- Invalid or malformed 0x address for owner, token, or spender returns an error
- Unsupported chain name causes a validation error
- Token contract does not implement ERC-20 allowance function (non-standard contract) may return zero or error
- RPC node unavailability on the target chain causes a timeout or upstream error
- Network congestion may cause slow response for certain chains

## How this service works

ERC-20 allowance an owner has granted a spender for one token: raw and human amount, with the token's symbol and decimals. unlimited is true when the allowance is at least 2^255, the usual approve-everything value. Read-only.

## Output

Returns a JSON object containing the raw uint256 allowance string, a human-readable decimal amount, a boolean 'unlimited' flag, the token symbol and decimals, the chain name, the owner and spender addresses, and a timestamp of when the check was performed. Also includes the RPC source used for the on-chain call.

## 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"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "owner",
      "token",
      "spender"
     ],
     "properties": {
      "chain": {
       "type": "string",
       "description": "base (default), ethereum, arbitrum, optimism or polygon"
      },
      "owner": {
       "type": "string",
       "description": "Token owner, 0x…"
      },
      "token": {
       "type": "string",
       "description": "ERC-20 contract, 0x…"
      },
      "spender": {
       "type": "string",
       "description": "Spender, 0x…"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "raw": "115792089237316195423570985008687907853269984665640564039457584007913082113074",
  "chain": "base",
  "owner": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
  "token": {
   "symbol": "USDC",
   "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "decimals": 6
  },
  "amount": 1.157920892373162e+71,
  "source": "https://base-rpc.publicnode.com (eth_call allowance, decimals, symbol)",
  "spender": "0x2626664c2603336E57B271c5C0b26F421741e481",
  "checkedAt": "2026-10-14T04:49:19.405Z",
  "unlimited": true,
  "disclaimer": "Information only, not financial advice."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-evm-erc-20-token-allowance-checker-5a6527fe/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.sitecheck-api.workers.dev](https://www.zero.xyz/host/api.sitecheck-api.workers.dev/llms.txt)