How to Use Python to Build Secure Blockchain Applications

Did you know it’s now possible to build blockchain applications, known also as decentralized applications (or “dApps” for short) in native Python? Blockchain development has traditionally required learning specialized languages, creating a barrier for many developers… until now. AlgoKit, an all-in-one development toolkit for Algorand, enables developers to build blockchain applications in pure Python.

This article will walk you through the benefits of building blockchain applications, why Python is an ideal choice for dApp development, how to set up your blockchain development environment, and how to start building secure blockchain applications in native Python.

Why build blockchain applications?

Blockchain application development goes far beyond creating a decentralized database and peer-to-peer transactions. It unlocks a new level of trust, security, and efficiency for various applications.

Guarantee tamper-proof records: Blockchain creates an immutable and transparent ledger, ensuring data security and eliminating the risk of manipulation.

Automate complex agreements: Smart contracts and atomic swaps eliminate the need for third-party verification, streamlining transactions and reducing costs.

Revolutionize asset ownership: Digitization allows for fractional ownership and secure trading of real-world assets.

Build innovative solutions: Python development skills can be used to create groundbreaking applications in AI, identity management, and secure IoT data exchange.

Why use Python to build blockchain applications?

Readability and maintainability: Python’s smooth syntax and robust tooling make it easier to write, understand, and modify code, especially when working on complex, powerful blockchain projects.

Integration with other technologies: Python works well with other technologies often used alongside blockchain, such as web development frameworks and machine learning libraries. This allows for building dApps that go beyond core blockchain functionality.

World-class developer experience: Python has a vast and active developer community, plus top-notch, comprehensive documentation and robust tools to support your Python and blockchain development journey.

How to set up your development environment to start building blockchain applications

The simplest way to build blockchain applications in Python is to download and install AlgoKit. This one-stop toolkit empowers you to build, launch, and deploy secure, production-ready decentralized applications on the Algorand blockchain.

With AlgoKit, you can set up your development environment and project folder and start building your project with just one command.

Download and install prerequisites

Ensure you have installed Python 3.12 or higher, pipx, Git, and Docker. On macOS, you will also need to install Homebrew.

Install AlgoKit

Open the command line/terminal and type "pipx install algokit". This will install AlgoKit so that you can use it in any directory.

Set up a local blockchain network

You can try out a private version of the Algorand blockchain on your computer.

Type “algokit localnet start” into the command line/terminal. This will create a local blockchain network running in a container using Docker. You can then check the Docker Desktop app to see it running.

To launch a browser-based blockchain explorer to visualize what is happening on this local network, type "algokit localnet explore".

Create a new project

Now that AlgoKit is installed, you can create a new project for your blockchain application.

First, run "algokit init". This will launch a guided process, and you will be prompted to answer a few quick questions to set up your project.

If this is your first time, start by selecting “smart contracts” to indicate you’re building a smart contract application.

Since you’ll be writing Python code, select “Python” as your language and pick a name for the folder that will store all your project’s files and a name for your application.

Finally, choose the “Production” template to set up a project ready for deployment.

The production template is like a pre-built starter kit for your Algorand project. It will give you a clear picture of how different parts like testing, continuous integration/continuous delivery (CI/CD), and deployment work together in a complete Algorand project. Then, select “Python” again.

Answer Y to the next questions to have AlgoKit install dependencies and initialize a Git repository for you.

Once you have completed the project generation process, open the project directory in your preferred code editor.

How to build secure blockchain applications in Python****Explore the code

The “Production” template will include a simple “hello world” smart contract found in "smart_contracts/hello_world/contract.py". This contract should look pretty familiar to Python developers with a couple of key differences.

The first thing to note is that we inherit “ARC4Contract” for our “HelloWorld” class. ARC4 is Algorand Request for Comment #0004 which defines the application binary interface (ABI) for Algorand methods. By inheriting from "ARC4Contract", we guarantee the contract is compliant with this standard that many tools in the Algorand ecosystem, including AlgoKit itself, use.

Above the actual “hello” method definition there is also a “@arc4.abimethod” decorator. This decorator exposes the method as a public method within our contract. Because this is an ARC4 ABI method, any tooling that supports the ABI can call this method with ease. AlgoKit also includes a client generator, which can generate a Python or TypeScript client to interact with all of the ABI methods you have defined.

Finally, you’ll notice that the argument and return type of our function is an "arc4.String". ARC4 also defines how we encode and decode data types when interacting with contracts. Because the Algorand Virtual Machine (AVM) does not support all the same features as a Python "str", we need to use the “arc4.String” type provided by the “algopy” module.

Compile and build

You can use “algokit project run build” to compile the smart contract written in native Python into TEAL, the bytecode language that the AVM can understand. Building also generates additional artifacts that can be used to make interactions with the contract easier, as we will see in the tests.

Interact and test

To see how contract interaction and testing are done, navigate to "tests/hello_world_test.py". Here you can see that we are using the HelloWorldClient that has been auto-generated by AlgoKit during the build step. This makes it very easy to interact with the contract and can be leveraged in tests, backend, or frontend development.

Write your code

After exploring this project and running your first "Hello World", you are ready to build on Algorand! You can turn the example contract into your own dApp, such as a marketplace, a manager of tokenized real-world assets, or an immutable data store on the chain.

Write your on-chain smart contract logic in contract.py and associated tests in "smart_contracts/tests". Re-run “algokit project run build” to re-compile, deploy, and test the contract in seconds.

You are now prepared to iterate quickly as you build your own application while AlgoKit takes care of the boilerplate code and development environment configuration.

For more tutorials about how to use Python to build on Algorand with AlgoKit, visit the AlgoDevs YouTube channel.

For more information on Algorand Python, refer to the documentation.

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