# ERC20 Token Allowance & Approval Checker

> ERC20 Token Allowance & Approval Checker is a paid API for AI agents from api.x402node.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Checks the exact ERC20 allowance an owner has granted to a spender contract on EVM chains, flagging unlimited approvals that may need revocation

## Facts

- Endpoint: GET https://api.x402node.dev/chain/token-approvals
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/erc20-token-allowance-approval-checker-1007c791
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_G5rXPK5TXZrfqKqhoE0lv

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-token-allowance-approval-checker-1007c791
```

Example prompt: Check how much USDC allowance my wallet 0xAbC...123 has granted to the Uniswap router contract 0xDef...456 on Ethereum — and flag it if it's an unlimited approval that I should consider revoking.

## When to prefer this

Use this endpoint when you need to audit a specific ERC20 token allowance granted by an owner to a particular spender on an EVM chain, especially to detect unlimited approvals that pose security risks. Prefer this over generic block explorers when you need programmatic, structured allowance data with automatic unlimited-approval flagging for revocation workflows.

## Known failure modes

- Invalid or non-existent token contract address returns error
- Owner or spender address not valid EVM format returns 400
- Unsupported EVM chain returns error
- Token contract is not ERC20-compliant returns error
- Network RPC timeout causes 500 or retry needed
- Missing required parameters returns 400 bad request

## How this service works

Check the exact ERC20 allowance an owner has granted to a spender contract, flagging unlimited approvals for revocation, on EVM chains. token allowance, approval check, unlimited approval, revoke allowance, spender allowance, wallet security Accepts payment on Base or Solana — either network works.

## Output

Returns the exact ERC20 allowance amount the owner has approved for the spender contract, whether the approval is unlimited (max uint256), and relevant token/chain context to help decide whether to revoke the approval.

## Example request

```json
{
 "chain": "ethereum",
 "owner": "0x1234567890123456789012345678901234567890",
 "token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
 "spender": "0xE592427A0AEce92De3Edee1F18E0157C05861564"
}
```

## 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": [
      "token",
      "owner",
      "spender"
     ],
     "properties": {
      "chain": {
       "type": "string",
       "description": "ethereum, base (default), arbitrum, optimism, polygon"
      },
      "owner": {
       "type": "string",
       "description": "Token owner address (required)"
      },
      "token": {
       "type": "string",
       "description": "ERC20 contract address (required)"
      },
      "address": {
       "type": "string",
       "description": "EVM/chain address (optional)"
      },
      "spender": {
       "type": "string",
       "description": "Spender contract address (required)"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc20-token-allowance-approval-checker-1007c791/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.x402node.dev](https://www.zero.xyz/host/api.x402node.dev/llms.txt)