# Joe EVM RPC – Chain ID Lookup

> Joe EVM RPC – Chain ID Lookup is a paid API for AI agents from joe-evm-rpc.marnick-yezo.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Returns the EVM chain ID for a specified network (Base or Ethereum) via a pay-per-call RPC endpoint.

## Facts

- Endpoint: GET https://joe-evm-rpc.marnick-yezo.workers.dev/api/chain/chain-id
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/joe-evm-rpc-chain-id-lookup-8ec0528f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_g5pTg3_3NAJMfK3jeriq_

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 joe-evm-rpc-chain-id-lookup-8ec0528f
```

Example prompt: What is the chain ID for the Base network right now — can you check via a live RPC call and give me the hex result?

## When to prefer this

Choose this endpoint when an AI agent needs a live, pay-per-call EVM chain ID lookup without managing its own RPC credentials. Ideal for agents operating on Base or Ethereum that need to programmatically verify the chain ID before signing transactions, deploying contracts, or switching networks. The x402 micropayment model ($0.001 USDC) makes it suitable for high-frequency automated queries with no subscription overhead.

## Known failure modes

- Invalid network parameter (not 'base' or 'ethereum') returns an error response
- Payment failure or insufficient USDC balance blocks the request under x402 protocol
- Network timeout from upstream RPC (mainnet.base.org or Ethereum node) causes delayed or failed response
- Malformed path parameter returns 4xx error

## How this service works

Live Base and Ethereum RPC for AI agents: block tip, balances, transactions, and ENS. $0.001 USDC per call on Base.

## Output

Returns a JSON object with a `data.result` field containing the chain ID as a hex string (e.g. '0x2105' for Base), plus metadata including the RPC URL used, network name, endpoint path, cost in USDC, and a unique request ID.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "pathParams": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "network": {
       "enum": [
        "base",
        "ethereum"
       ],
       "type": "string",
       "default": "base",
       "description": "EVM network. Default base."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {
   "result": "0x2105"
  },
  "meta": {
   "rpc": "https://mainnet.base.org",
   "network": "base",
   "endpoint": "/api/chain/chain-id",
   "cost_usdc": "0.001",
   "request_id": "00000000abcdef01"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/joe-evm-rpc-chain-id-lookup-8ec0528f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from joe-evm-rpc.marnick-yezo.workers.dev](https://www.zero.xyz/host/joe-evm-rpc.marnick-yezo.workers.dev/llms.txt)