Vyper Programming Language: Smart Contract Developer Guide

Did you know that over 7,959 smart contracts written in Vyper secure more than $2.3 billion of Total Value Locked (TVL) across leading blockchains? To realize the significance of this, consider that there are 23 countries whose entire economies are valued less than that. 

Although not as popular as Solidity, the Vyper smart contract programming language is powerful and especially well-suited for creating smart contracts on Ethereum Virtual Machine (EVM) compatible networks. As security vulnerabilities continue challenging the blockchain industry, Vyper's focus on simplicity and safety makes it an attractive option for developers and protocols.

So, this contract-oriented programming language is gaining traction. Let’s explore what it is and the value of its features for smart contract development.

What is Vyper programming language?

Vyper is a pythonic programming language specifically designed for the EVM. It was created in 2017 in response to security concerns in smart contract development, emphasizing three core principles: security, simplicity, and auditability.
Unlike Solidity, Vyper intentionally limits certain programming features to reduce the potential for vulnerabilities, make code more secure, and facilitate auditing. The goal is to ensure the development of secure, efficient smart contracts.

Vyper’s design principles help achieve this:

1. Security-first: Every design choice prioritizes security, excluding “risky” features even at the cost of convenience.
   
2. Minimalist feature set: A limited feature set reduces attack surfaces, making smart contracts safer and easier to audit.
   
3. Python-like syntax: Clean and readable, Vyper’s syntax makes it easy to understand for Python developers. This lowers the learning curve and reduces errors.
   
4. Strong typing system: Vyper enforces strict type-checking on variables, function inputs, and outputs. This prevents unintended type conversions and ensures predictable contract behavior.
   
5. Built-in protection: Vyper includes automatic safeguards such as overflow checks, bounds validation for arrays and strings, and reentrancy protection. These reduce the risk of common smart contract vulnerabilities.

These foundational principles set the stage for Vyper's distinctive features, which we’ll explore next.

Vyper’s core features 

Vyper’s features make it exceptionally well-suited for writing smart contracts on EVM blockchains.

Built-in security features

The language offers several basic security measures to prevent common vulnerabilities:

• Automatic overflow checking: All arithmetic operations are automatically checked for overflow conditions, preventing numerical errors that could lead to contract vulnerabilities.
  
• Explicit bounds checking: Array and string operations include built-in bounds checking, eliminating buffer overflow vulnerabilities common in other languages.
  
• Gas limit protection: Vyper allows for the computation of precise upper bounds for gas consumption. This helps prevent denial-of-service (DoS) attacks based on gas exhaustion.
  
• Reentrancy protection: The language includes built-in protection against reentrancy attacks, a common vulnerability in smart contracts.
  
  

‍

These built-in security features do come with potential downsides.

Vyper’s deliberate tradeoffs to prioritize security

By focusing on security and auditability, Vyper intentionally excludes several programming features commonly found in other languages:

1. No function overloading: Unlike Solidity or Python, Vyper disallows multiple functions with the same name but different parameters. Each function must have a unique name, eliminating ambiguity and easing audits.
   
2. No operator overloading: Unlike Python or C++, Vyper prevents redefining operators to avoid hidden logic risks. Operators retain standard behavior, ensuring predictability and security.
3. No recursive calling: The Vyper programming language has completely eliminated recursive functions to enforce predictable gas consumption and avoid gas limit attacks.
   
4. No infinite-length loops: All loops must have fixed bounds when writing Vyper smart contracts. This ensures that gas limits can be calculated precisely and DoS attacks prevented.
   
5. No modifiers: Function modifiers, which allow hidden preconditions, postconditions, or state changes, are excluded. Instead, inline assert statements make code more readable and auditable.
   
6. No class inheritance: Excluding inheritance simplifies program understanding. And eliminates the need to track behavior across multiple files or precedence rules.
   
7. No inline assembly: Prevents the introduction of hard-to-track, low-level operations, preserving code readability and traceability.

‍

Now that you have a high-level understanding of the Vyper programming language, here’s how to get started building with it.

Install Vyper

To use Vyper, you must set up your development environment. Here's a step-by-step guide to get you started:

Prerequisites

First, make sure your setup meets the minimum requirements:

1. Python environment:
   
   • Python 3.6 or higher installed
   • Package Installer for Python (uv, pip) manager available
   • Virtual environment (recommended)
     
     
2. Development tools:
   
   • Git (for version control)
   • A code editor with Python support
   • Command-line interface (CLI) access
     
     

Installation methods

Using uv (recommended)

Since Vyper is a command line tool, we should install Vyper in its own virtual isolated environment. This way, if you download other Python tools, you will not run into dependency management issues. For example, if you have a Python project that depends on 3.10 of Vyper, but you want to use 4.0 of Vyper in your command line, you can have your project use 3.10 since your command line Vyper is isolated!

‍

uv tool install vyper

# Verify installation
vyper --version

‍

However, if you want to add Vyper to a Python project, you can run:

‍

uv venv
source .venv/bin/activate
uv add vyper

# Verify installation
vyper --version

‍

Using pip 

This method installs Vyper directly from the Python Package Index (PyPI). Pip is the most common way people install packages into a Python virtual environment. 

‍

# Create and activate a virtual environment (recommended)
python -m venv vyper-env
source vyper-env/bin/activate  # On Windows: vyper-env\Scripts\activate

# Install Vyper
pip install vyper

# Verify installation
vyper --version

‍

‍Security pro tip: An isolated dev environment ensures that dependencies remain separate from your system installation.  This reduces the risk of conflicts with other Python projects, and potential malicious Python scripts being run.

Using Docker

Docker allows you to run Vyper in a containerized environment, avoiding the need to install it directly on your machine while increasing security. So, it’s an ideal option if you want a clean, portable setup without modifying your local environment.

‍

# Pull the latest Vyper Docker image
docker pull vyperlang/vyper

# Run Vyper in a container
docker run -v $(pwd):/code vyperlang/vyper /code/your_contract.vy

‍

This approach is particularly useful when working on multiple projects or collaborating with others.

Building from source

Some developers may want the latest features or to contribute to Vyper’s development. In that case, building the compiler from its source code is the best option.

‍

# Clone the repository
git clone https://github.com/vyperlang/vyper.git
cd vyper

# Install dependencies
pip install -e .

‍

This method provides access to the most recent updates and allows you to explore the inner workings of the Vyper compiler. However, it may require more maintenance than prebuilt options.

So, choose the method that best fits your development needs and workflow.

Post-installation setup

After installing Vyper, complete these steps:

1. Configure your Integrated Development Environment (IDE):
   
   • Install Vyper syntax highlighting extensions (e.g., tintinweb and trocher)
     
   • Set up linting tools (programs or extensions that analyze code for errors, bugs, stylistic issues, or suspicious constructs)
     
   • Configure compilation settings that allow you to compile Vyper code directly within the IDE, streamlining the development workflow.
     
     
2. Set up development tools:
   
   • Install testing frameworks like Foundry or Moccasin to streamline the development and testing of your Vyper smart contracts. Moccasin, in particular, offers a Pythonic approach to managing contract deployment and testing and integrates seamlessly with Vyper.
     
   • Configure your deployment tools to simplify interacting with the blockchain, managing deployment parameters, and monitoring results.
     
   • Set up a local blockchain environment. This is a simulated blockchain, such as Foundry’s anvil, that runs locally on your computer. It allows you to develop, test, and debug smart contracts without interacting with a live network. This approach saves time and avoids unnecessary costs.
     

And now you’re ready to start writing code.

Writing smart contracts in Vyper

Let's explore an example of how to write a smart contract using the Vyper programming language. This contract implements a basic ERC-20 token with several security features:

# pragma version 0.4.0
"""
@license MIT
@title ERC20
@author You!
@dev This is a basic (not fully correct) ERC20 contract
"""

# Contract state variables
owner: public(address)
total_supply: public(uint256)
balances: public(HashMap[address, uint256])
allowances: public(HashMap[address, HashMap[address, uint256]])

# Events for tracking contract activity
event Transfer:
    sender: indexed(address)
    receiver: indexed(address)
    amount: uint256

event Approval:
    owner: indexed(address)
    spender: indexed(address)
    amount: uint256

@deploy
def __init__(_total_supply: uint256):
    """
    @notice Initialize the token contract
    @param _total_supply The initial total supply of tokens
    """
    self.owner = msg.sender
    self.total_supply = _total_supply
    self.balances[msg.sender] = _total_supply

@external
def transfer(_to: address, _value: uint256) -> bool:
    """
    @notice Transfer tokens to another address
    @param _to The recipient address
    @param _value Amount of tokens to transfer
    @return Success of the transfer
    """
    assert self.balances[msg.sender] >= _value, "Insufficient balance"
    assert _to != empty(address), "Cannot transfer to zero address"

    self.balances[msg.sender] -= _value
    self.balances[_to] += _value
    log Transfer(msg.sender, _to, _value)
    return True

@external
def approve(_spender: address, _value: uint256) -> bool:
    """
    @notice Approve an address to spend tokens on your behalf
    @param _spender The address to approve
    @param _value Amount of tokens to approve
    @return Success of the approval
    """
    assert _spender != empty(address), "Cannot approve zero address"
    
    self.allowances[msg.sender][_spender] = _value
    log Approval(msg.sender, _spender, _value)
    return True

‍

Understanding Vyper’s code structure

1. State variables
   
   • Clear visibility modifiers use public to ensure transparency: Visibility modifiers determine how and where variables can be accessed. public allows variables to be read externally.
     
   • Explicit type declarations for all variables for enhanced security: Defining explicit data types (e.g., uint256, address) prevents unexpected behavior caused by type mismatches. It also helps the contract function as intended.
     
   • Use of HashMaps for efficient storage through optimized data structures: A HashMap is a key-value storage structure used to store balances and allowances. It allows for fast lookups, making it an efficient tool for managing complex datasets like user accounts.
     
2. Events
   
   • Indexed parameters enable efficient filtering: Indexed parameters in events allow logs to be easily queried and filtered. Thus, users and third-party tools can track activities, such as transfers between accounts.
     
   • Clear documentation of transfer and approval activities: Events like Transfer and Approval explicitly document the movement of tokens and permissions. This makes it easier for developers and auditors to follow the contract’s behavior.
     
   • Standardized event structures for better interoperability: Using well-known event formats ensures compatibility with external tools and platforms, such as blockchain explorers or wallets.
     
3. Functions
   
   • Built-in security checks prevent common vulnerabilities: Functions help ensure sufficient balances before transfers or verify that recipient addresses are valid. These measures prevent typical issues like overspending or transfers to invalid addresses.
     
   • Clear error messages for failed assertions aid debugging: ​​Error messages describe the reason for a failure. It helps developers quickly identify and fix problems during testing or audits.

So, what is the difference between Vyper and Solidity?

‍

Vyper vs Solidity: full comparison

Vyper and Solidity are both EVM-compatible smart contract languages, but they serve different needs. Understanding their differences helps developers choose the right tool.

• Syntax and learning curve: Solidity's syntax resembles C++ and JavaScript. In contrast, Vyper’s Python-inspired syntax is widely used, simpler, and more accessible. Making it particularly suitable for beginners or those with a Python background.
  
• Flexibility vs. simplicity: Solidity offers a multitude of features, including dynamic arrays, inheritance, and modifiers, allowing developers to build highly customizable and complex smart contracts. However, this flexibility comes with a steeper learning curve and a greater potential for vulnerabilities. On the other hand, Vyper, by design, intentionally sacrifices many of these features to prioritize clarity, predictability, and security. This ensures the code is easier to audit and maintain.
  
• Tooling and community support: Solidity benefits from extensive community support, a large ecosystem of active developers, tools like Remix, and OpenZeppelin’s contract library, and comprehensive documentation. While growing, Vyper has fewer tools and less community support. This can be challenging for developers looking for ready-made solutions.
  
• Security features: Vyper’s deliberate exclusion of features minimizes the attack surface. This makes it an ideal choice for projects where security is paramount. Solidity, while flexible, requires developers to implement these safeguards manually, increasing the risk of human error.
  
• Bytecode efficiency and gas costs: Vyper’s refusal to allow dynamically sized variables means it doesn’t need to keep a free memory pointer at the bytecode level. This can make Vyper contracts slightly more gas-efficient in certain scenarios. However, both are less optimized than lower-level languages like Huff and Yul, which minimize abstraction for lower gas costs.
  ‍
  

Thought both languages compile to EVM bytecode, they serve different purposes. Solidity excels in flexibility and ecosystem support, while Vyper prioritizes clarity and reliability. Thus, it is a strong choice for projects that demand robust, easily auditable code.

Now, let’s see how Vyper works in practice. 

‍

Real-world applications using the Vyper programming language

Decentralized Finance (DeFi)

• Curve Finance uses Vyper for its automated market maker (AMM) contracts. The platform specifically chose Vyper for its mathematically intensive stablecoin trading pools because of:
  
  • Superior handling of decimal point precision in financial calculations
  • Built-in overflow protection for large numerical operations
  • Clearer code organization for complex mathematical formulas
    
• Lido Finance uses Vyper for secure and efficient staking contracts and has also invested $300,000 to date in Vyper’s development to achieve:
  
  • Stronger security, reducing risks in staking contracts.
  • Improved reliability, supporting audits and bug bounties.
    

Security-critical applications

• Multi-signature wallets such as SuperSig built using Vyper  benefit from:
  
  • Simplified code flow that makes security audits more straightforward
  • Clear state variable management for tracking owner permissions
  • Explicit function declarations that prevent signature validation bypasses
    
• Token vesting contracts like Yearn Finance’s vesting escrow contracts choose Vyper because:
  
  • Time-based calculations benefit from Vyper's precise decimal handling
  • Lock-up periods are clearly defined and easily auditable
  • Gas optimization features help reduce distribution costs

Still, there are a few things you need to keep in mind when building with Vyper.

Best practices for Vyper development

When creating Vyper-based Ethereum smart contracts, follow established best practices to ensure security and efficiency.

Security should be the primary focus when developing smart contracts. Here are key practices to follow:

1. Development workflow:

• Always use the latest Vyper version to benefit from security updates
• Implement thorough error handling for all possible scenarios
• Follow established gas optimization patterns
• Maintain clear and comprehensive documentation
• Use version control and proper code review processes
  
  

2. Code audits:
   

• Conduct regular security audits throughout development
• Implement comprehensive test coverage for all code paths
• Perform gas optimization reviews to ensure efficient operation
• Test boundary conditions extensively
• Verify all mathematical operations for accuracy
  
  

So, how do you start learning Vyper? 

‍

Where to learn the Vyper programming language?

To learn Vyper, the following resources offer comprehensive guides and courses:

• Cyfrin Updraft provides a range of courses tailored for different proficiency levels:
  
  • Introduction to Python and Vyper Smart Contract Development is ideal for beginners. It covers the basics of Vyper and smart contract development.
    
  • Intermediate Python and Vyper Smart Contract Development dives into testing, deploying contracts on zkSync using Moccasin. It also teaches you how to launch your first cryptocurrency.
    
  • Advanced Python Smart Contract Development Course guides you through advanced Vyper concepts. It covers building DeFi stablecoins, deploying on ZKsync with Moccasin, Python fuzzing techniques, and creating customizable NFTs. Simultaneously, you’ll complete five real-world projects to enhance your blockchain engineering skills.
    
    
• Vyper by Example: A repository of examples and video explanations demonstrating how Vyper works (powered by Cyfrin).
  
  
• Vyper’s official documentation offers detailed explanations of syntax, features, and best practices. This makes it an essential reference for developers at all levels.
  
  
• Vyper.fun: An interactive platform where you can learn Vyper by building a Pokémon game, making the learning process engaging and hands-on.

These resources collectively offer a solid foundation for mastering Vyper, catering to various learning preferences and skill levels.

Conclusion

Vyper is a powerful tool for developing secure smart contracts. It offers unparalleled security, clarity, and auditability for critical blockchain projects. While not a complete replacement for Solidity, it’s the ideal choice when security and code simplicity are priorities.

So, level up your smart contract development and start learning Vyper on Cyfrin Updraft today!