# Polygon PoS ERC-20 Allowance Checker

> Polygon PoS ERC-20 Allowance Checker is a paid API for AI agents from ca-tax-api-mainnet.lxtap.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-23).

Returns the ERC-20 allowance a spender has on Polygon PoS, including whether it is effectively unlimited, the owner's current balance, and the spendable amount right now.

## Facts

- Endpoint: GET https://ca-tax-api-mainnet.lxtap.workers.dev/polygon/allowance?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/polygon-pos-erc-20-allowance-checker-0a0381f0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8pKwh7BIcNh2ZPQPIkAq7

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 polygon-pos-erc-20-allowance-checker-0a0381f0
```

Example prompt: What's the current ERC-20 allowance for spender 0xE592427A0AEce92De3Edee1F18E0157C05861564 on token 0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174 from owner 0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B on Polygon PoS, and can they actually move all of it right now given the owner's balance?

## When to prefer this

Use this endpoint when you specifically need ERC-20 allowance data on the Polygon PoS network, including whether an approval is unlimited and the effective spendable amount factoring in the owner's balance. Prefer this over raw RPC calls when you want enriched, ready-to-use allowance intelligence rather than a raw uint256, and when operating on Polygon PoS (not Ethereum mainnet, Arbitrum, Base, or other chains).

## Known failure modes

- Invalid Ethereum address format for token, owner, or spender returns a 400 validation error
- Token address that is not a deployed ERC-20 contract on Polygon PoS returns an error or zero values
- Polygon PoS RPC node unavailability causes a 502 or timeout
- Missing required query parameters (token, owner, or spender) returns a 400 error
- Payment not included or insufficient USDC causes a 402 Payment Required response

## How this service works

Pay-per-call data for AI agents, paid in USDC on Base with x402: token risk checks (rug check) on Base, Ethereum, Arbitrum, Optimism, Polygon and Solana, onchain reads (balances, transactions, gas, contracts, NFTs, whale trades, new pools, ENS and Basenames), ECB exchange rates, and Canadian sales tax and business days.

## Output

Returns the raw allowance granted by the owner to the spender, a boolean indicating whether the approval is effectively unlimited (max uint256), the owner's current ERC-20 token balance on Polygon PoS, and the effective amount the spender can move right now (the minimum of the allowance and the owner's balance).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "token",
      "owner",
      "spender"
     ],
     "properties": {
      "owner": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "Address that granted the approval"
      },
      "token": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "ERC-20 contract on Polygon PoS"
      },
      "spender": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "Address allowed to spend"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "raw": "115792089237316195423570985008687907853269984665640564039457584007913129639935",
  "chain": "polygon",
  "owner": "0x357542d88744DB4BFfE8F90008138dDc4a10cdC3",
  "token": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
  "symbol": "USDC",
  "spender": "0x429eba38eF16A42C62b497C22A4662C45b37f848",
  "allowance": "115792089237316195423570985008687907853269984665640564039457584007913129.639935",
  "unlimited": true,
  "ownerBalance": "0",
  "spendableNow": "0"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/polygon-pos-erc-20-allowance-checker-0a0381f0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ca-tax-api-mainnet.lxtap.workers.dev](https://www.zero.xyz/host/ca-tax-api-mainnet.lxtap.workers.dev/llms.txt)