# EVM Chain Read – ERC-20 Allowance

> EVM Chain Read – ERC-20 Allowance is a paid API for AI agents from chain-read.frcompanycheck.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-28).

Returns the ERC-20 token allowance that a spender is approved to transfer on behalf of an owner, on Base or Robinhood Chain, paid per-call via x402 USDC.

## Facts

- Endpoint: GET https://chain-read.frcompanycheck.workers.dev/v1/%7Bchain%7D/erc20/allowance/%7Btoken%7D/%7Bowner%7D/%7Bspender%7D?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-28
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evm-chain-read-erc-20-allowance-09b2a90b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_232G_nRotZuLsgJKhn5Qm

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 evm-chain-read-erc-20-allowance-09b2a90b
```

Example prompt: On Base (chain 8453), what is the current ERC-20 allowance for the USDC token at 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48, where the owner is 0xAbCd1234...5678 and the spender is the Uniswap v3 router at 0xE592427A...?

## When to prefer this

Use this endpoint when you need a lightweight, pay-per-call ERC-20 allowance read on Base or Robinhood Chain without managing your own RPC infrastructure or API keys. It is ideal for AI agents that need on-demand blockchain state reads priced at $0.002 USDC per call, especially when integrating DeFi workflows that require approval checks before swap or transfer transactions.

## Known failure modes

- Invalid or non-checksummed address returns an error or zero allowance
- Unsupported chain ID returns a routing error
- Non-ERC-20 contract address (e.g. an EOA or non-standard contract) may return 0 or an RPC error
- x402 payment failure (insufficient USDC balance or misconfigured payment header) results in 402 response blocking the read
- Network/RPC congestion on the underlying public node may cause timeouts

## How this service works

Pay-per-call EVM reads on Base (8453) and Robinhood Chain (4663): native balance, block tip, ERC-20 meta/balance/allowance, is-contract. Public RPCs, no API key. x402 USDC on Base.

## Output

A JSON object with a single field `allowance` containing the uint256 integer representing the number of token units the spender is authorized to transfer on behalf of the owner. A value of 0 means no approval exists.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "allowance": 0
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/evm-chain-read-erc-20-allowance-09b2a90b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from chain-read.frcompanycheck.workers.dev](https://www.zero.xyz/host/chain-read.frcompanycheck.workers.dev/llms.txt)