getblockheader - Bitcoin Cash

Example code for the getblockheader JSON-RPC method. Complete guide on how to use getblockheader JSON-RPC in GetBlock Web3 documentation.

This method returns the header of a block given its hash. With verbose set to false it returns the hex-encoded header; with true it returns a JSON object of header fields.

Parameters

Parameter	Type	Required	Description
blockhash	string	Yes	The block hash
verbose	boolean	No	true for a JSON object, false for hex-encoded data. Default true

Request

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "getblockheader",
    "params": ["0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc", true],
    "id": "getblock.io"
}'

bitcoinjs-lib

example.js

const axios = require('axios');
const { data } = await axios.post('https://go.getblock.io/<ACCESS-TOKEN>/', {
  jsonrpc: '2.0', method: 'getblockheader',
  params: ['0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc', true], id: 'getblock.io'
});
console.log(data.result.height, data.result.time);

Request

example.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'getblockheader',
        'params': ["0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc", true],
        'id': 'getblock.io'
    }
)

print(response.json()['result'])

Rust

example.rs

use reqwest::Client;
use serde_json::{json, Value};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();

    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "getblockheader",
            "params": ["0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc", true],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;

    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "error": null,
    "id": "getblock.io",
    "result": {
        "hash": "0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc",
        "confirmations": 1197,
        "height": 684634,
        "version": 1073733632,
        "versionHex": "3fffe000",
        "merkleroot": "d14c9f467c4bdd5135837696150ab5f52f3f5043de324ca4e5766b195b9f8f37",
        "time": 1617180599,
        "mediantime": 1617176373,
        "nonce": 3669423616,
        "bits": "170cdf6f",
        "difficulty": 21865558044610.55,
        "chainwork": "00000000000000000000000000000000000000001b633a711a2334c78a29bb40",
        "nTx": 2815,
        "previousblockhash": "000000000000000001d3a318372df5d1eec54462a0d7471ae1cdf49838f793dd",
        "nextblockhash": "000000000000000000006d8e1eb870bd281b30ed621acf6b8d6af2a3c7ab61f1"
    }
}

Response Parameters

Parameter	Type	Description
error	null|object	Error object when the call fails, otherwise null
id	string	Request identifier matching the request
result	object	Block header object when verbose is true, or a hex string when false

Result Object

Field	Type	Description
hash	string	Block hash
height	numeric	Block height
merkleroot	string	Merkle root of the block's transactions
time	numeric	Block time as a Unix timestamp
nonce	numeric	Nonce used in the proof-of-work
bits	string	Compact form of the target threshold
previousblockhash	string	Hash of the parent block

Use Cases

• Lightweight Sync: Fetch headers without downloading full block bodies

• Proof of Work: Read bits and nonce to verify a block's difficulty target

• Chain Walking: Follow previousblockhash to traverse the header chain

• Timestamp Checks: Read mediantime for time-based consensus rules

Error Handling

Error Code	Message	Description
-8	Invalid parameter	blockhash is not a valid 64-character hex string
-5	Block not found	No block with the given hash exists on this node
-32603	Internal error	Node failed to read the block from disk