getblocktemplate - Zcash

Example code for the getblocktemplate JSON-RPC method. Сomplete guide on how to use the getblocktemplate JSON-RPC method in GetBlock.io Web3 documentation.

This method returns a template for constructing a candidate block for mining. Miners and mining pools call this to receive the current block header parameters, coinbase output structure, and the set of mempool transactions that should be included. Zcash uses the Equihash proof-of-work algorithm, so template consumers need to solve the Equihash puzzle for the provided parameters.

Parameters

Parameter	Type	Required	Description
template_request	object	No	Template request parameters (see below). Defaults to the standard template request

Template Request

Field	Type	Required	Description
mode	string	No	template (default) requests a new template; proposal submits a proposed block
capabilities	array of string	No	Client capabilities (coinbasetxn, coinbasevalue, proposal)
longpollid	string	No	Long-polling ID for waiting on updated templates

Request

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "getblocktemplate",
    "params": [
        {
            "mode": "template",
            "capabilities": [
                "coinbasetxn",
                "coinbasevalue"
            ]
        }
    ],
    "id": "getblock.io"
}'

Axios

example.js

const axios = require('axios');

const response = await axios.post('https://go.getblock.io/<ACCESS-TOKEN>/', {
    jsonrpc: '2.0',
    method: 'getblocktemplate',
    params: [
        {
            "mode": "template",
            "capabilities": [
                "coinbasetxn",
                "coinbasevalue"
            ]
        }
    ],
    id: 'getblock.io'
}, {
    headers: { 'Content-Type': 'application/json' }
});

console.log(response.data.result);

Request

example.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'getblocktemplate',
        'params': [
        {
            "mode": "template",
            "capabilities": [
                "coinbasetxn",
                "coinbasevalue"
            ]
        }
    ],
        'id': 'getblock.io'
    }
)

print(response.json())

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": "getblocktemplate",
            "params": [
        {
            "mode": "template",
            "capabilities": [
                "coinbasetxn",
                "coinbasevalue"
            ]
        }
    ],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;
    
    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": {
        "capabilities": [
            "proposal"
        ],
        "version": 4,
        "previousblockhash": "00000000018bb43cadf5b4c8a2e7f9d0e1a6b3c8d5e4f2a1b0c9d8e7f6a5b4c3",
        "blockcommitmentshash": "5eae9c5cbe0e8d3e2f5cd8b0a4e3b1f2c9d8e7f6a5b4c3d2e1f0a9b8c7d6e5f4",
        "lightclientroothash": "3a2b1c9d8e7f6a5b4c3d2e1f0a9b8c7d6e5f4a3b2c1d0e9f8a7b6c5d4e3f2a1b",
        "finalsaplingroothash": "01a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1",
        "defaultroots": {
            "merkleroot": "9c8f0e4f8d2e7c6b5a4f3e2d1c0b9a8e7f6d5c4b3a2b1c9d8e7f6a5b4c3d2e1f",
            "chainhistoryroot": "b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3",
            "authdataroot": "9c8f0e4f8d2e7c6b5a4f3e2d1c0b9a8e7f6d5c4b3a2b1c9d8e7f6a5b4c3d2e1f"
        },
        "transactions": [],
        "coinbasetxn": {
            "data": "0400008085202f890100000000000000000000000000000000...",
            "hash": "2b1c9d8e7f6a5b4c3d2e1f0a9b8c7d6e5f4a3b2c1d0e9f8a7b6c5d4e3f2a1b09",
            "authdigest": "0000000000000000000000000000000000000000000000000000000000000000",
            "depends": [],
            "fee": 0,
            "sigops": 0,
            "required": true
        },
        "longpollid": "00000000018bb43cadf5b4c8a2e7f9d0e1a6b3c8d5e4f2a1b0c9d8e7f6a5b4c3-47",
        "target": "00000000005cea00000000000000000000000000000000000000000000000000",
        "mintime": 1747852500,
        "mutable": [
            "time",
            "transactions",
            "prevblock"
        ],
        "noncerange": "00000000ffffffff",
        "sigoplimit": 20000,
        "sizelimit": 2000000,
        "curtime": 1747852800,
        "bits": "1d00ffff",
        "height": 2856343
    }
}

Response Parameters

Parameter	Type	Description
version	integer	Block version to use
previousblockhash	string	Hash of the parent block
blockcommitmentshash	string	Block commitments hash to include in the header
finalsaplingroothash	string	Final Sapling root at this block height
defaultroots	object	Precomputed default root hashes for header construction
transactions	array of object	Mempool transactions selected for inclusion
coinbasetxn	object	Coinbase transaction template with reward split
target	string	Difficulty target to solve for
mintime	integer	Minimum allowed block timestamp
mutable	array of string	Fields the miner may modify
noncerange	string	Nonce range hint
sigoplimit	integer	Maximum signature operations allowed in the block
sizelimit	integer	Maximum block size in bytes
curtime	integer	Current timestamp suggested by the node
bits	string	Compact difficulty target
height	integer	Height at which this block will be included

Use Cases

• Solo Mining: Miners request templates to construct candidate blocks for Equihash solving

• Mining Pool Coordination: Pool servers fetch templates and distribute solving work to participant miners

• Block Proposal Verification: Submit constructed blocks in proposal mode to check validity before broadcasting

• Long-Poll Template Updates: Use longpollid to wait for new templates when the chain tip advances

Error Handling

Error Code	Message	Description
-8	Invalid parameter	Template request parameters are malformed
-32602	Invalid params	Template request structure is invalid
-32603	Internal error	Node failed to build the template