# EVM Block Header by Block Hash

> EVM Block Header by Block Hash is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-01).

Retrieves the block header for a specific EVM block identified by its 32-byte hash, across ten supported EVM-compatible chains.

## Facts

- Endpoint: POST https://twin.unykorn.org/evm-block-by-hash?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evm-block-header-by-block-hash-382b13ef
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1aDlYtruTc70HCTFEZ-yl

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 evm-block-header-by-block-hash-382b13ef -d '<json body>'
```

Example prompt: Can you fetch the block header for block hash 0x3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b on Ethereum?

## When to prefer this

Choose this endpoint when you already know a block's 32-byte hash and need its header data (timestamp, miner, gas, parent hash, etc.) on any of ten major EVM chains without running your own node. It is ideal for agents performing blockchain audits, cross-chain verification, or transaction provenance lookups where the block hash is the known anchor point rather than the block number.

## Known failure modes

- Invalid block hash format (not a 64-char hex with 0x prefix) — returns validation error
- Block hash not found on the specified chain — returns not-found or null result
- Unsupported chain name provided — schema enum validation failure
- Payment failure or insufficient USDC balance — x402 payment required error
- Network timeout or node unavailability on the target chain — upstream error

## How this service works

Block header by block hash — Genesis402 / UnyKorn Operator Network

## Output

Returns a JSON object confirming success, the endpoint type, and a payment receipt (including tx_hash, amount_usd, and receipt_id), along with a generated_at ISO8601 timestamp. The actual block header fields (number, timestamp, miner, gas, parent hash, etc.) are returned as part of the response payload.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "params": {
   "type": "object",
   "properties": {
    "hash": {
     "type": "string",
     "pattern": "^0x[0-9a-fA-F]{64}$"
    },
    "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-block-by-hash",
  "receipt": {
   "tx_hash": "0x<64hex>",
   "amount_usd": 0.003,
   "receipt_id": "g402-<16hex>"
  },
  "generated_at": "<iso8601>"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/evm-block-header-by-block-hash-382b13ef/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)