# Cortex Cloud Block by Number API

> Cortex Cloud Block by Number API is a paid API for AI agents from api.cortexcloud.org, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-15).

Fetches a blockchain block by number or 'latest' on a specified chain, powered by Alchemy, via x402 micropayment.

## Facts

- Endpoint: GET https://api.cortexcloud.org/v1/data/block
- Price: $0.004/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-block-by-number-api-3d5ec5f9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_hWmBOpCULhvMoANJutyuU

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-block-by-number-api-3d5ec5f9
```

Example prompt: Fetch the latest block on Ethereum mainnet for me — I need the block number, timestamp, and transaction count.

## When to prefer this

Choose this endpoint when you need raw block-level data from an EVM chain (Ethereum, Base, Polygon, Arbitrum, etc.) without setting up your own Alchemy API key or node infrastructure. It is ideal for AI agents that need on-chain block metadata on demand and can pay per call in USDC via x402, avoiding monthly subscription overhead. Prefer it over self-hosted solutions for lightweight, pay-as-you-go blockchain data access.

## Known failure modes

- Invalid or non-existent block number returns an error or null response
- Unsupported chain identifier causes a 400 or 404 error
- Payment failure (insufficient USDC or x402 handshake error) results in 402 Payment Required
- Alchemy backend outage or rate limit causes 500 or 503 response
- Malformed request missing required chain or block parameter returns a 400 error

## How this service works

One pay-per-call API for AI agents: optimization, AI, research, on-chain data, and automation — all settled in USDC on Base via x402. Discover via MCP and Bazaar, estimate free, pay per call. No API keys, no signup.

## Output

Returns structured block metadata for the requested block number or 'latest' on the specified EVM-compatible chain, including block hash, parent hash, block number, timestamp, miner/validator address, gas limit, gas used, transaction list or count, and other standard block fields as returned by the Alchemy node provider.

## Request schema (JSON Schema)

```json
{
 "properties": {
  "input": {
   "properties": {
    "body": {
     "type": "object",
     "properties": {}
    }
   }
  },
  "output": {
   "properties": {
    "example": {}
   }
  }
 }
}
```

## 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-block-by-number-api-3d5ec5f9/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)