# Keyronne Chain Block Header Lookup

> Keyronne Chain Block Header Lookup is a paid API for AI agents from keyronne.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-14).

Fetch block header details (timestamp, miner, gas used/limit, base fee, tx count, size) by block number, hash, or 'latest' on major EVM chains

## Facts

- Endpoint: POST https://keyronne.com/api/chain-block
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/keyronne-chain-block-header-lookup-21311cb2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cb_Cszi1g2aZ2z_g_VL5G

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 keyronne-chain-block-header-lookup-21311cb2 -d '<json body>'
```

Example prompt: Can you grab the block header for the latest block on Base — I need the timestamp, miner, gas used, base fee, and transaction count?

## When to prefer this

Use this endpoint when you need block-level metadata (timestamp, miner, gas metrics, base fee, tx count) on a specific EVM chain without needing full transaction data. Prefer this over a transaction lookup endpoint when you want chain-wide block info rather than a specific tx, and over a gas price endpoint when you need historical block data rather than current fee suggestions.

## Known failure modes

- Block number not found on the specified chain — returns error indicating invalid block
- Invalid or malformed block hash — returns parsing or not-found error
- Unsupported chain value outside the allowed enum — returns validation error
- Downstream RPC node unavailable or rate-limited — returns 5xx or timeout
- Malformed JSON body — returns 400 bad request

## How this service works

Fetch a block header by number, hash, or "latest" on Ethereum, Base, Arbitrum, Optimism, Polygon, or BNB Chain: timestamp, miner, gas used/limit, base fee, transaction count, size. Public JSON-RPC, no API keys. POST a JSON body like: {"chain":"base","block":"latest"}

## Output

Returns a JSON object with block header fields including timestamp, miner address, gas used, gas limit, base fee per gas, transaction count, block size, and block hash for the requested block on the specified chain.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "block": {
   "description": "Block number, \"latest\" (default), or a 0x block hash."
  },
  "chain": {
   "enum": [
    "ethereum",
    "base",
    "arbitrum",
    "optimism",
    "polygon",
    "bsc"
   ],
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/keyronne-chain-block-header-lookup-21311cb2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from keyronne.com](https://www.zero.xyz/host/keyronne.com/llms.txt)