# EIP-155 Chain ID Lookup via UnyKorn Node

> EIP-155 Chain ID Lookup via UnyKorn Node is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Returns the EIP-155 chain ID for a specified EVM-compatible network, confirmed directly from the node itself.

## Facts

- Endpoint: POST https://twin.unykorn.org/evm-chain-id?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/eip-155-chain-id-lookup-via-unykorn-node-0cebe482
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yeYV0Giu28MsgbE516ytI

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 eip-155-chain-id-lookup-via-unykorn-node-0cebe482 -d '<json body>'
```

Example prompt: What is the EIP-155 chain ID for Base, confirmed directly from the node?

## When to prefer this

Prefer this endpoint when you need a node-authoritative confirmation of an EVM chain ID rather than a hardcoded constant — useful for security-sensitive signing workflows, cross-chain routing validation, or when you want a receipted, auditable chain ID lookup across the ten most popular EVM networks (Ethereum, Base, Polygon, Arbitrum, Optimism, BSC, Avalanche, Gnosis, Linea, Scroll).

## Known failure modes

- Unsupported chain name returns validation error — only the ten enumerated chains are accepted
- Node connectivity issues may cause timeout or 5xx error
- Invalid or missing 'chain' parameter results in schema validation failure
- Payment failure via x402 protocol may prevent execution

## How this service works

EIP-155 chain id, confirmed from the node itself — Genesis402 / UnyKorn Operator Network

## Output

Returns a JSON object with ok status, the type field set to 'evm-chain-id', the chain ID value confirmed from the live node, a payment receipt containing tx_hash, amount_usd, and receipt_id, and a generated_at ISO8601 timestamp.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "params": {
   "type": "object",
   "properties": {
    "chain": {
     "enum": [
      "ethereum",
      "base",
      "polygon",
      "arbitrum",
      "optimism",
      "bsc",
      "avalanche",
      "gnosis",
      "linea",
      "scroll"
     ],
     "type": "string"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "type": "evm-chain-id",
  "receipt": {
   "tx_hash": "0x<64hex>",
   "amount_usd": 0.25,
   "receipt_id": "g402-<16hex>"
  },
  "generated_at": "<iso8601>"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/eip-155-chain-id-lookup-via-unykorn-node-0cebe482/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from twin.unykorn.org](https://www.zero.xyz/host/twin.unykorn.org/llms.txt)