# ERC20 Token Allowance Checker

> ERC20 Token Allowance Checker is a paid API for AI agents from api.x402node.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Returns the ERC20 allowance an owner has granted to a spender, including raw and formatted amounts, token symbol, and decimals across five EVM chains

## Facts

- Endpoint: GET https://api.x402node.dev/chain/token-allowance
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/erc20-token-allowance-checker-e9093296
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ldmInHKlwIZPeVkd1z-TA

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-checker-e9093296
```

Example prompt: Check how much USDC allowance the wallet 0xAbC...123 has approved for the Uniswap v3 router 0xE592...1F on Ethereum mainnet — give me the formatted amount with the token symbol.

## When to prefer this

Use this endpoint when you need to quickly audit how much token spending authority an owner has delegated to a specific spender on any of the five major EVM chains, especially for DeFi safety checks, revoke helper workflows, or pre-transaction approval validation. Prefer this over on-chain RPC calls directly when you need a formatted, symbol-aware response without setting up your own blockchain node.

## Known failure modes

- Invalid or malformed owner/spender/token address returns an error
- Unsupported chain identifier returns a chain not supported error
- Token contract address is not a valid ERC20 contract, causing a call revert
- Zero allowance is a valid successful response, not an error
- Network congestion or RPC timeout may cause intermittent failures

## How this service works

Check the ERC20 allowance an owner has granted a spender, returns raw and formatted amount with token symbol and decimals on five EVM chains. token allowance, erc20 approval check, spender allowance, approval audit, revoke helper data Accepts payment on Base or Solana — either network works.

## Output

Returns the raw allowance value (in smallest token units), a human-readable formatted amount, the token symbol, and the number of decimals, for the specified owner-spender pair on one of five supported EVM chains (Ethereum, Base, Arbitrum, Optimism, Polygon).

## Example request

```json
{
 "chain": "ethereum",
 "owner": "0x1234567890123456789012345678901234567890",
 "token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
 "spender": "0x0987654321098765432109876543210987654321"
}
```

## 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": "Owner address (required)"
      },
      "token": {
       "type": "string",
       "description": "ERC20 contract (required)"
      },
      "spender": {
       "type": "string",
       "description": "Spender address (required)"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc20-token-allowance-checker-e9093296/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)