Web3.py is a Python library that allows developers to interact with Ethereum and other EVM-compatible blockchains. It helps developers retrieve blockchain data, check wallet balances, read smart contracts, and build blockchain applications using Python.

For Python developers interested in Web3 development, Web3.py provides a practical starting point.

1. What Is Web3.py?

Web3.py is a Python library for communicating with Ethereum nodes through JSON-RPC.

With Web3.py, developers can:

• Connect Python applications to Ethereum networks.
• Retrieve blockchain data and block information.
• Check ETH balances for public wallet addresses.
• Read data from deployed smart contracts.
• Build and sign blockchain transactions.
• Develop tools for decentralized applications (dApps).

2. Install Web3.py

Create a Python virtual environment:

python -m venv .venv

Activate it on Windows:

.venv\Scripts\activate

On Linux or macOS:

source .venv/bin/activate

Install Web3.py:

pip install web3

Verify the installation:

python -c "import web3; print(web3.__version__)"

3. Connect Python to Ethereum

You need an Ethereum node RPC endpoint to communicate with the blockchain. For learning, you can use an RPC endpoint connected to the Sepolia testnet.

Store your endpoint in an environment variable named SEPOLIA_RPC_URL.

import os
from web3 import Web3

rpc_url = os.environ.get("SEPOLIA_RPC_URL")

if not rpc_url:
    raise ValueError("Please configure SEPOLIA_RPC_URL")

w3 = Web3(Web3.HTTPProvider(rpc_url))

if not w3.is_connected():
    raise ConnectionError("Could not connect to Ethereum")

print("Connected successfully")
print("Chain ID:", w3.eth.chain_id)

The Sepolia testnet chain ID is 11155111. Checking the chain ID helps verify that you are connected to the intended network.

4. Retrieve the Latest Block

After connecting, you can retrieve the latest block number.

latest_block = w3.eth.block_number

print("Latest block:", latest_block)

To retrieve more information about the latest block:

block = w3.eth.get_block("latest")

print("Block number:", block["number"])
print("Block hash:", block["hash"].hex())
print("Timestamp:", block["timestamp"])
print("Transactions:", len(block["transactions"]))

This is useful for building blockchain explorers, monitoring tools, and blockchain analytics applications.

5. Check an Ethereum Wallet Balance

Web3.py can retrieve the ETH balance of any public wallet address without requiring its private key.

from web3 import Web3

address = Web3.to_checksum_address(
    "0x0000000000000000000000000000000000000000"
)

balance_wei = w3.eth.get_balance(address)
balance_eth = w3.from_wei(balance_wei, "ether")

print("ETH balance:", balance_eth)

The example uses Ethereum's special zero address. Replace it with a valid public address to check another wallet.

Ethereum balances are returned in wei, the smallest denomination of ETH. The from_wei() method converts the balance into ETH.

Security tip: Never share your private key or recovery phrase. They are not needed to check a public wallet balance.

6. Read Data from a Smart Contract

Web3.py can interact with deployed smart contracts using an Application Binary Interface (ABI).

An ABI describes the functions exposed by a smart contract.

For example, if a deployed contract has a public name() function that returns a string, you can read it as follows:

from web3 import Web3

contract_address = Web3.to_checksum_address(
    "YOUR_DEPLOYED_CONTRACT_ADDRESS"
)

contract_abi = [
    {
        "inputs": [],
        "name": "name",
        "outputs": [
            {
                "internalType": "string",
                "name": "",
                "type": "string"
            }
        ],
        "stateMutability": "view",
        "type": "function"
    }
]

contract = w3.eth.contract(
    address=contract_address,
    abi=contract_abi
)

contract_name = contract.functions.name().call()

print("Contract name:", contract_name)

Replace the placeholder address with a deployed contract that supports the specified function.

The .call() method reads contract data without broadcasting a transaction or requiring a private key.

7. Web3.py Project Ideas

Here are some beginner-friendly projects you can build using Web3.py.

Ethereum Wallet Balance Checker

Accept a public wallet address and display its ETH balance.

Blockchain Explorer

Display block numbers, hashes, timestamps, and transaction counts.

Smart Contract Reader

Retrieve public data from a deployed smart contract.

Transaction Tracker

Accept a transaction hash and display its status and details.

Token Information Dashboard

Read token metadata and balances from compatible ERC-20 contracts.

Start with read-only applications before experimenting with transactions that modify blockchain state.

8. Common Problems and Solutions

Connection errors: Verify the RPC endpoint, network connectivity, and provider limits.

Invalid address errors: Check the address format and use Web3.to_checksum_address().

Contract call failures: Confirm that the contract exists on the connected network and that the ABI matches the deployed contract.

Incorrect network: Check w3.eth.chain_id before interacting with contracts.

Unexpected transaction costs: Use a testnet while learning and understand gas fees before sending transactions on a production network.

Conclusion

Web3.py makes it possible to combine Python programming with Ethereum blockchain functionality. By learning to connect to an RPC endpoint, retrieve blocks, check wallet balances, and read smart contract data, developers can build a strong foundation for advanced Web3 applications.

A good next step is to create a command-line application that accepts an Ethereum address and displays its ETH balance and the latest block number.

For further learning, visit the official Web3.py documentation:

https://web3py.readthedocs.io/

Blockchain technology is increasingly used to build applications that require transparency, verifiable records, and decentralized data management. For computer science and information technology students, blockchain projects provide an opportunity to explore smart contracts, decentralized applications (DApps), cryptography, and distributed systems through practical implementation.

Choosing the right blockchain project depends on your programming experience, available development tools, project complexity, and the problem you want to solve. Here are several ideas that students can explore, from beginner-friendly applications to more advanced implementations.

1. Blockchain-Based Certificate Verification

Digital certificates can be difficult to verify when records are stored across different institutions. A blockchain-based certificate verification system can help make issued credentials easier to validate.

Key features:

• Generate a unique certificate identifier.
• Store a certificate hash on a blockchain.
• Allow users to verify certificate authenticity.
• Provide a verification interface for employers or institutions.

Technologies: Solidity, an Ethereum-compatible development environment, a web frontend, and a suitable storage system.

2. Decentralized Document Verification

This project explores how blockchain can help verify whether a document has changed after it was issued.

A system can calculate a cryptographic hash of a document and record the hash or its reference through a smart contract. When someone submits the document for verification, the application recalculates the hash and compares the result.

Learning outcomes: Cryptographic hashing, smart-contract development, transaction handling, and application integration.

3. Supply Chain Tracking System

A blockchain-based supply chain application can record important events as a product moves between suppliers, distributors, and retailers.

Key features:

• Record product registration and transfer events.
• Track timestamps and authorized participants.
• Allow users to view a product's recorded history.
• Identify missing or inconsistent records.

Blockchain can make recorded events more difficult to alter retrospectively, but it does not automatically guarantee that the original information entered into the system is accurate.

4. Decentralized Voting Prototype

A decentralized voting prototype can demonstrate how smart contracts enforce voting rules.

A student implementation might include voter eligibility checks, one-vote-per-authorized-address restrictions, vote recording, and result calculation.

This should be treated as an educational prototype. A production election system requires additional security, privacy, accessibility, and independent auditing.

5. Crowdfunding Using Smart Contracts

A blockchain crowdfunding application can demonstrate how contributions and funding conditions are handled through programmable contracts.

Key features:

• Create a fundraising campaign.
• Set a funding target and deadline.
• Record contributions.
• Release funds when predefined conditions are met.
• Return contributions when a campaign fails, according to the contract's rules.

This project introduces students to contract state, events, transaction testing, and handling failure conditions.

6. How to Choose a Blockchain Project Domain

Before beginning development, identify the problem you want to solve and the skills you want to demonstrate.

1. Technical prerequisites: Decide whether you need JavaScript, Solidity, cryptography, databases, or frontend development.
2. Project scope: Start with a small, testable use case before adding advanced features.
3. Practical demonstration: Ensure you can demonstrate the complete workflow, rather than only present a theoretical design.
4. Security: Test access permissions, input validation, transaction failures, and smart-contract edge cases.
5. Documentation: Explain the architecture, design decisions, limitations, and testing process.

Students exploring more project topics can refer to this resource: Blockchain Projects.

7. Development Tools for Blockchain Projects

The tools depend on the blockchain platform and application you choose.

• Solidity: A programming language for smart contracts on Ethereum-compatible platforms.
• Remix IDE: A browser-based environment for writing, compiling, and testing Solidity contracts.
• Hardhat: A development environment for compiling, testing, and deploying smart contracts.
• Ethers.js: A JavaScript library for interacting with Ethereum-compatible networks.
• Local blockchain networks or testnets: Environments for testing applications without using real funds.

For beginners, a sensible workflow is to develop a small contract, write automated tests, deploy it to a local network, and then build a simple interface to interact with it.

Conclusion

Blockchain projects can help students understand smart contracts, decentralized applications, transaction processing, and cryptographic verification. Projects such as certificate verification, document integrity checking, supply chain tracking, and crowdfunding offer practical ways to explore these concepts.

The best project is not necessarily the most complex one. Choose a well-defined problem, build a working prototype, test its limitations, and document what you learned. This approach makes the project more useful as a technical learning experience and a portfolio demonstration.