# ERC-20 Token Allowance Lookup

> ERC-20 Token Allowance Lookup is a paid API for AI agents from ai-data-marketplace-1042299154756.us-central1.run.app, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-15).

Looks up the current ERC-20 token spending allowance granted by an owner wallet to a spender address on Base, Ethereum, or Arbitrum.

## Facts

- Endpoint: GET https://ai-data-marketplace-1042299154756.us-central1.run.app/api/v1/erc20_allowance
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/erc-20-token-allowance-lookup-9beefb28
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_o4LaL0t9E6pPsXCnOj6xt

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-lookup-9beefb28
```

Example prompt: Check how much USDC the Uniswap v3 router (0xE592427A0AEce92De3Edee1F18E0157C05861564) is allowed to spend from wallet 0xAbCd...1234 on Base — I want to know the exact allowance and whether any approval is present.

## When to prefer this

Use this endpoint when you need a lightweight, pay-per-call lookup of ERC-20 token allowances across Base, Ethereum, or Arbitrum without setting up your own blockchain RPC infrastructure. Ideal for security audits, pre-transaction checks, and DeFi workflow automation where you need to verify approvals granted to a specific spender.

## Known failure modes

- Invalid token contract address returns an error or empty result
- Unsupported chain identifier causes a bad request response
- Owner or spender address formatted incorrectly returns a failure
- Network timeout or RPC node unavailability may cause transient errors
- Token contract that does not implement ERC-20 allowance method may return an error

## How this service works

Read the current ERC-20 allowance for an owner, spender, and token from a supported EVM network without signing or broadcasting.

## Output

Returns a JSON object with the token symbol, a boolean indicating whether any approval exists (approval_present), the raw allowance as a string integer (allowance_raw), and the human-readable formatted allowance (allowance_formatted), along with a success flag.

## 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": "base, ethereum, or arbitrum; defaults to base."
      },
      "owner": {
       "type": "string",
       "description": "Wallet that granted the allowance."
      },
      "token": {
       "type": "string",
       "description": "ERC-20 token contract address."
      },
      "spender": {
       "type": "string",
       "description": "Address authorized to spend."
      }
     },
     "additionalProperties": true
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "success",
      "symbol",
      "allowance_raw",
      "allowance_formatted",
      "approval_present"
     ],
     "properties": {
      "symbol": {
       "type": "string"
      },
      "success": {
       "type": "boolean"
      },
      "allowance_raw": {
       "type": "string"
      },
      "approval_present": {
       "type": "boolean"
      },
      "allowance_formatted": {
       "type": "string"
      }
     },
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "symbol": "USDC",
  "success": true,
  "allowance_raw": "0",
  "approval_present": false,
  "allowance_formatted": "0.0"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc-20-token-allowance-lookup-9beefb28/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ai-data-marketplace-1042299154756.us-central1.run.app](https://www.zero.xyz/host/ai-data-marketplace-1042299154756.us-central1.run.app/llms.txt)