getLatestBlockhash - Solana

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

This method returns the most recent blockhash and the last block height at which it remains valid. Every transaction must reference a recent blockhash to be accepted by the cluster.

Parameters

Parameter	Type	Required	Description
config	object	No	Configuration object controlling commitment

Config Object

Field	Type	Required	Description
commitment	string	No	Commitment level: processed, confirmed, or finalized. Defaults to finalized
minContextSlot	number	No	Minimum slot the request can be evaluated at

Request

cURL

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

@solana/web3.js

example.js

const { Connection } = require('@solana/web3.js');

const connection = new Connection('https://go.getblock.io/<ACCESS-TOKEN>/', 'confirmed');

const latestBlockhash = await connection.getLatestBlockhash();

console.log(latestBlockhash.blockhash, latestBlockhash.lastValidBlockHeight);

Request

example.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'getLatestBlockhash',
        'params': [{"commitment": "confirmed"}],
        '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": "getLatestBlockhash",
            "params": [{"commitment": "confirmed"}],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;

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

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": {
        "context": {
            "apiVersion": "2.3.6",
            "slot": 397234561
        },
        "value": {
            "blockhash": "9zJqLXK9pMhQZ4tGqVvUcxrKpKQ3pMSJ1nZmVeXtBqTd",
            "lastValidBlockHeight": 375812409
        }
    }
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	object	RPC response object where value holds the blockhash and its expiry block height

Value Object

Field	Type	Description
blockhash	string	Base58-encoded blockhash to reference in a transaction
lastValidBlockHeight	number	Last block height at which the blockhash is still accepted

Use Cases

• Transaction Building: Attach a recent blockhash before signing and sending

• Retry Windows: Stop rebroadcasting once block height passes lastValidBlockHeight

• Confirmation Strategy: Pair with a signature subscription for expiry-aware confirmation

• Durable Nonce Fallback: Detect when a durable nonce is needed for long signing flows

Error Handling

Error Code	Message	Description
-32602	Invalid params	Unrecognized commitment level in the config object
-32603	Internal error	Node failed to read the recent blockhash queue
-32005	Node is unhealthy	The node has fallen behind and would return a stale blockhash