# Cortex Cloud Ethereum RPC via x402

> Cortex Cloud Ethereum RPC via x402 is a paid API for AI agents from api.cortexcloud.org, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Executes Ethereum JSON-RPC calls (e.g. eth_blockNumber, eth_getBalance, eth_call) with per-call USDC micropayment on Base via x402 — no API key required.

## Facts

- Endpoint: GET https://api.cortexcloud.org/x402/v1/rpc/ethereum
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cortex-cloud-ethereum-rpc-via-x402-9eaf3560
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_rkLrl_U3ULeLbdSpmd1h_

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 cortex-cloud-ethereum-rpc-via-x402-9eaf3560
```

Example prompt: Can you call eth_getBalance for wallet address 0xAbCd...1234 on Ethereum mainnet and tell me the current ETH balance? Pay with USDC on Base via x402 — no API key needed.

## When to prefer this

Choose this endpoint when you need keyless, subscription-free Ethereum JSON-RPC access paid per call in USDC via x402 — ideal for AI agents that lack pre-registered API credentials, need one-off blockchain lookups, or operate in environments where managing API keys is impractical. Prefer over Infura/Alchemy when avoiding upfront account creation or monthly billing is a priority.

## Known failure modes

- Unsupported or misspelled RPC method name returns a JSON-RPC error with code -32601
- Malformed params array causes a -32602 invalid params error
- Insufficient x402 payment or expired payment header results in HTTP 402 rejection before execution
- Rate limiting or node unavailability returns HTTP 503 or a timeout
- Calling state-mutating methods (e.g. eth_sendRawTransaction) may be blocked or unsupported on this read-oriented endpoint

## How this service works

OpenAI-compatible AI and data API for agents. Pay per call in USDC on Base via x402 — no API keys, no subscriptions, no lock-in.

## Output

A JSON-RPC response object containing an id, jsonrpc version string, and a result field whose value depends on the method called — e.g. a hex-encoded balance for eth_getBalance, a hex block number for eth_blockNumber, or encoded return data for eth_call. Errors return a structured error object with code and message.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "id": {
   "type": "integer"
  },
  "method": {
   "type": "string"
  },
  "params": {
   "type": "array"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "format": "application/json",
 "example": {}
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cortex-cloud-ethereum-rpc-via-x402-9eaf3560/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.cortexcloud.org](https://www.zero.xyz/host/api.cortexcloud.org/llms.txt)