Solidity and Vyper smart contract development and code reading
The ability to design, write, audit, and comprehend smart contracts on Ethereum Virtual Machine (EVM) compatible blockchains using Solidity and Vyper languages.
This skill directly enables the creation of decentralized financial (DeFi) protocols, NFT platforms, and DAOs, which handle billions in digital assets. It is critical for reducing catastrophic financial risk through secure code and enabling novel, trustless business models.
1Careers
1Categories
9.2 Avg Demand
20%
Avg AI Risk
How to Learn Solidity and Vyper smart contract development and code reading
1. Core Blockchain & EVM Fundamentals: Understand state, transactions, gas, and the Ethereum Yellow Paper. 2. Solidity Syntax & Data Types: Master storage vs. memory, mappings, structs, and visibility modifiers (public/private/internal). 3. Tooling Setup: Install Hardhat/Foundry, MetaMask, and deploy to a testnet like Sepolia.
1. Security Patterns & Vulnerability Identification: Study reentrancy, integer overflow, and front-running; use tools like Slither and Mythril. 2. Intermediate Contract Architecture: Design upgradeable contracts (Transparent Proxy, UUPS) and implement proper access control (OpenZeppelin's AccessControl). 3. Gas Optimization: Learn assembly (Yul), bit packing, and efficient loop structures. Common mistake: Underestimating the impact of unbounded loops and storage writes.
1. Formal Verification & Complex Mechanism Design: Apply tools like Certora Prover to mathematically prove contract invariants; design intricate tokenomics, AMMs, or lending protocols. 2. Cross-Contract & Layer 2 Integration: Architect systems that interact with oracles (Chainlink), bridges, and performant L2s (Optimism, Arbitrum). 3. Mentorship & Standards Setting: Lead code reviews, establish team coding standards, and contribute to EIPs (Ethereum Improvement Proposals).
Practice Projects
Beginner
Project
ERC-20 Token & Simple Faucet
Scenario
Create a basic fungible token with mint/burn capabilities and a public faucet that dispenses a fixed amount to any address once every 24 hours.
How to Execute
1. Use the OpenZeppelin Wizard to generate an ERC-20 contract with a 'mint' function restricted to the owner. 2. Implement the Faucet contract with a mapping to track last claim time and a 'claim' function with the 24h modifier. 3. Write unit tests in Hardhat/Foundry to test minting, access control, and the claim cooldown. 4. Deploy both contracts to a testnet and interact via a simple frontend script.
Intermediate
Project
Upgradeable Vault with Fee-on-Transfer
Scenario
Build a vault contract that accepts deposits of any ERC-20 token (including those with transfer fees) and issues shares, using the UUPS proxy pattern for future upgrades.
How to Execute
1. Design the Vault contract using the EIP-4626 (Tokenized Vault Standard) as a reference. Implement the UUPS upgradeable proxy pattern. 2. Handle fee-on-transfer tokens by comparing the contract's balance before and after the transfer to determine the actual amount received. 3. Implement comprehensive tests simulating various token behaviors (standard, fee-on-transfer, rebasing). 4. Deploy the proxy and implementation, perform an upgrade on testnet to a V2 with a new feature, and verify state persistence.
Advanced
Project
Security Audit & Formal Verification of a DeFi Lending Market
Scenario
Audit a simplified lending protocol (inspired by Aave/Compound V2) that allows users to supply assets as collateral and borrow other assets, with a liquidation mechanism.
How to Execute
1. Conduct a manual line-by-line audit, mapping out all state variables, external calls, and potential attack vectors (flash loan exploits, oracle manipulation, economic attacks). 2. Use static analysis tools (Slither, Mythril) to identify low-hanging vulnerabilities. 3. Write formal verification specifications in Certora or Halmos to mathematically prove critical invariants (e.g., 'solvency of the system', 'user cannot withdraw more collateral than their debt allows'). 4. Produce a professional audit report detailing findings, risk levels, and specific code fixes.
Tools & Frameworks
Development & Testing Frameworks
HardhatFoundry (Forge, Anvil, Cast)Remix IDE
Hardhat offers a rich plugin ecosystem for TypeScript-based testing/deployment. Foundry uses Solidity for tests (Forge), providing blazing speed and deep EVM testing capabilities. Remix is for rapid prototyping and learning.
Security & Analysis Tools
SlitherMythrilCertora ProverAderyn
Slither (static analysis) detects common vulnerabilities. Mythril (symbolic execution) finds deeper bugs. Certora Prover performs formal verification. Aderyn is a newer, fast static analyzer for large codebases.
OpenZeppelin provides audited, reusable contract components. Studying EIPs is essential for interoperability. Solmate is a gas-optimized alternative. Reading Uniswap V3 Core is a masterclass in advanced Solidity.
Infrastructure & Monitoring
TenderlyEtherscanBlocknative
Tenderly provides transaction simulation, debugging, and monitoring. Etherscan is for contract verification and on-chain data inspection. Blocknative for mempool monitoring and front-running analysis.
Interview Questions
Answer Strategy
Structure the answer: 1) Define reentrancy (external call allows malicious contract to callback and re-enter). 2) Explain CEI (update state before external call). 3) Note limitation: CEI does not protect against cross-function reentrancy where an attacker re-enters a different function that shares the same state variable. 4) Mention the solution: using a reentrancy guard modifier (e.g., OpenZeppelin's nonReentrant). Sample: 'Reentrancy occurs when an external call gives control to a malicious contract that calls back into the vulnerable function before state updates. CEI mitigates this by ensuring state changes happen before the call. However, it's insufficient for cross-function reentrancy, where an attacker re-enters via a different function sharing the same state, requiring a dedicated reentrancy guard for full protection.'
Answer Strategy
Tests architectural thinking and awareness of standards. The candidate should reference EIP-20 (Transfer events) and EIP-712 (structured data hashing) for secure delegation signatures, and the `DelegateChanged` event (from EIP-5805/Compound's model) for indexing. Sample: 'I would implement a `delegate(address delegatee)` function that updates the delegate mapping for the caller. For gas efficiency and user convenience, I would also support delegated voting via a signed message (EIP-712) so users can delegate without a transaction. Crucially, I must emit a `DelegateChanged(delegator, fromDelegate, toDelegate)` event, which is the standard for off-chain services like Snapshot to track delegation changes accurately.'
Careers That Require Solidity and Vyper smart contract development and code reading