⛓️

Top 48 Blockchain / Web3 / Solidity Interview Questions & Answers (2026)

48 Questions 20 Beginner 18 Intermediate 10 Advanced

About Blockchain / Web3 / Solidity

This technology is widely used in software development and is a frequent topic in technical interviews at companies of all sizes.

What to Expect in a Blockchain / Web3 / Solidity Interview

Interviews cover both foundational concepts and practical application of this technology, with questions ranging from definitions to architectural decision-making.

How to Use This Guide

Work through questions in order of difficulty to build your understanding progressively. Bookmark challenging questions and revisit them before your interview.

Curated by Tech Baithak Editorial Team · Last updated: May 2026

Beginner 20 questions

Core concepts every Blockchain / Web3 / Solidity developer must know.

01 What is blockchain? 02 What is a distributed ledger? 03 What is a block in a blockchain? 04 What is a node in a blockchain network? 05 What is cryptocurrency? 06 What is Bitcoin? 07 What is Ethereum? 08 What is a smart contract? 09 What is Web3? 10 What is Solidity? 11 What is a wallet in blockchain? 12 What is a public key and private key in blockchain? 13 What is a consensus mechanism? 14 What is Proof of Work (PoW)? 15 What is Proof of Stake (PoS)? 16 What is a decentralized application (DApp)? 17 What is an NFT (Non-Fungible Token)? 18 What is DeFi (Decentralized Finance)? 19 What is a gas fee in Ethereum? 20 What is an ABI (Application Binary Interface) in Ethereum?

Intermediate 18 questions

Practical knowledge for developers with hands-on experience.

01 How does Ethereum's EVM (Ethereum Virtual Machine) work? 02 What is a Solidity contract structure? 03 What are the data types in Solidity? 04 What is the difference between `memory` and `storage` in Solidity? 05 What are Solidity modifiers? 06 What are Solidity events? 07 What is the ERC-20 token standard? 08 What is the ERC-721 token standard? 09 What is Web3.js and what is it used for? 10 What is ethers.js? 11 What is IPFS and how is it used with blockchain? 12 What is a DAO (Decentralized Autonomous Organization)? 13 What is MetaMask? 14 What is Hardhat and how is it used for smart contract development? 15 What is the difference between mainnet, testnet, and local network? 16 What is Chainlink and why is it important for smart contracts? 17 What is the difference between Layer 1 and Layer 2 in blockchain? 18 What is a transaction hash in Ethereum?

Advanced 10 questions

Deep expertise questions for senior and lead roles.

01 What are common smart contract vulnerabilities (reentrancy, overflow, etc.)? 02 How does the Ethereum PoS consensus mechanism work after The Merge? 03 What is the difference between optimistic rollups and ZK-rollups? 04 What is a flash loan and how is it used in DeFi? 05 How do you optimize gas usage in Solidity? 06 What is the Proxy pattern in Solidity for upgradeable contracts? 07 What is MEV (Miner Extractable Value)? 08 How does the ERC-1155 token standard differ from ERC-20 and ERC-721? 09 What is the Account Abstraction (ERC-4337) proposal? 10 How do you audit a smart contract for security vulnerabilities?

Back to All Topics 48 questions total