Build a local blockchain explorer from scratch

As a developer, you’re no stranger to building tools and exploring blockchains. However, when using third-party blockchain explorers (like Blockscout, Etherscan, or Infura), you’re often limited in the number of requests per second (RPS) you can handle before hitting your internet connection’s bandwidth limit. But what if you want to have more control over your own blockchain? Want to build a local full node explorer that lets you query the blockchain without relying on external APIs?

The case for an open source project

In this article, we’ll explore the benefits of building an open source blockchain explorer from scratch and show you how to do it in a few simple steps.

Why Create Your Own Blockchain Explorer?

There are several benefits to creating your own blockchain explorer:

• More Control: Having full control over your code base allows you to ensure that everything works as expected without relying on third-party services.

• Scalability: As the number of users grows, a local full node explorer allows for more parallel connections, leading to faster performance and higher availability.

• Security: With direct access to blockchain data, you can implement robust security measures such as encryption and authentication to protect your user data.

The Basics: Creating a Local Full Node Explorer

To create a full local node explorer, we will use Python as the programming language. We will focus on creating a simple and lightweight implementation that uses only the Ethereum blockchain protocol.

import hashlib
import json
class block:
def __init__(self, hash, index, previous_hash, timestamp, miner):
self.hash = hash
self.index = index
self.previous_hash = previous_hash
self.timestamp = timestamp
self.miner = miner

Step 1: Configure the Ethereum Node

First, we need to create a local Ethereum node using Web3.py. We will use the „ethers” library to connect our blockchain.

from web3 import Web3
w3 = Web3(Web3.HTTPProvider(' 
Swap to the local Ethereum network

Step 2: Create a Block

Now that our node is set up, let’s create a new block. We use the „createTransaction” method to generate the transaction and add it to the blockchain.

def create_block(data):
return w3.eth.getTransactionCount(w3.currentProvider)

Step 3: Sign the Block

Before we can send the block to the network, we need to sign it with our account’s private key. We’ll use the „signTransaction” method to do this.

def sign_block(tx_data):
return w3.eth Account.sign_transaction([tx_data], w3.eth.getTransactionCount(w3.currentProvider)).signedTransaction

Step 4: Add the Block to the Blockchain

Now that we have the signed transaction, let’s add it to the blockchain using the add_block method.

def add_block(block_data):
return w3.eth.sendrawtransaction(block_data)

Putting it all together

Here is a simple example of how you can use these steps to create a complete local node explorer:

„` python

import hashlib

import json

class block:

def __init__(self, hash, index, previous_hash, timestamp, miner):

self.hash = hash

self.index = index

self.previous_hash = previous_hash

self.timestamp = timestamp

me.miner = miner

def create_block(data):

return w3.eth.getTransactionCount(w3.currentProvider)

def sign_block(tx_data):

return w3.eth.Account.sign_transaction([tx_data], w3.eth.getTransactionCount(w3.currentProvider)).signedTransaction

def add_block(block_data):

returns w3.eth.