Blockchain Interview Questions and Answers

Are you a Blockchain Developer seeking a job in one of the top US MNCs? Or, are you a recruiter from a top US MNC looking for an excellent Blockchain Developer? In either case, you have landed on the right page.

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 Interview questions

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Blockchain technology is revolutionizing the way we do business. As this technology continues to evolve, so does the need for developers and engineers with expertise in this field. Companies are, therefore, racing to hire people with blockchain skills to help build their products and services. However, the interview process can be daunting, given the complexity of this technology. That's why it's essential for you, as a hiring manager, to prepare the right questions so you can identify the right candidate for your team.

To help you out, we've compiled a list of blockchain interview questions and answers to prepare you for your next hiring process. Use these questions and answers to understand the applicant's knowledge and experience with blockchain technology and determine if they're the right fit for your team.

What Is a Blockchain Developer?

Before delving into the blockchain interview questions, it's essential to understand who a blockchain developer is. It's also vital to understand their role in the software development process.

According to Coursera, a blockchain developer is an engineer responsible for building and deploying blockchain-based applications. They also develop distributed apps (dApps) on various platforms.

There are two types of blockchain developers:

  • Core blockchain developers. These engineers are responsible for developing and maintaining the blockchain network's core infrastructure. This may include building consensus mechanisms, designing node architecture, coding smart contracts, and designing blockchain solutions.
  • Blockchain software developers. These developers build blockchain applications on top of the underlying architecture. They use programming languages like JavaScript, Python, and Solidity.

Blockchain Developer Roles & Responsibilities

Before hiring a blockchain developer for your team, you should understand exactly what they do so you can tailor a compelling Blockchain developer job description to attract top talent.

In general,  blockchain developers must have a strong understanding of blockchain architecture. This includes the ability to design and deploy complete systems. They must also be knowledgeable about the various protocols involved in blockchain development. Additionally, they should write efficient code for the distributed ledger system. They must also have a firm grasp of consensus algorithms and cryptographic algorithm development.

Based on the type of blockchain developer your company needs, here are the roles and responsibilities of each type:

Core Blockchain Developer Roles and Responsibilities

  • Designing blockchain solutions for clients or internal projects
  • Developing decentralized applications (dApps)
  • Writing consensus algorithms to validate blockchain transactions
  • Debugging and troubleshooting issues related to the blockchain network

Blockchain Software Developer Roles and Responsibilities

  • Developing and testing blockchain applications on various platforms
  • Writing code to interact with blockchain systems
  • Integrating blockchain APIs into existing systems
  • Designing user interfaces for blockchain applications

Blockchain Interview Questions (with Answers)

Now that you know who a blockchain developer is, it's time to dive into the interview questions. We'll discuss these questions in three levels: beginner, intermediate, and expert.

Beginner-Level Blockchain Interview Questions

At the beginner level, you will test the candidate's basic knowledge and understanding of blockchain. These interview questions are perfect for a candidate who is looking to get started in the field.

Technical Blockchain Interview Questions

  • What is blockchain?

The candidate should explain that  blockchain is a distributed digital ledger system that allows for secure, transparent, and immutable transactions.

  • What are the different types of blockchain?

The candidate should mention the three main types of blockchain. These are public blockchain, private blockchain, and consortium blockchain. They should also explain all three types in detail. A public blockchain is open and accessible to everyone. A private blockchain is only accessible to and managed by a single entity or organization. A consortium blockchain is accessible to and managed by multiple organizations.

  • How would you explain blockchain to someone unfamiliar with the technology?

The candidate should give an example of blockchain and explain how it works. They should also explain the different blockchain components. These include miners, nodes, and consensus mechanisms.

  • What are the advantages of blockchain?

The candidate should explain that blockchain improves security, transparency, immutability, and trust. They should also explain how blockchain technology reduces costs, increases efficiency, and provides greater flexibility in transactions.

  • What is the difference between blockchain and traditional databases?

The candidate should explain that blockchain is a distributed digital ledger system. Traditional databases, on the other hand, have a central authority and are managed by a single entity. Blockchain also improves security, transparency, immutability, and trust when compared to traditional databases.

  • What kind of records can you find in a blockchain database?

The candidate should explain that blockchain databases store both block records and transactional records. Transactional records are stored in blocks, which have a timestamp and a hash. Block records are stored in a chain, which contains the link to the previous block.

  • What are some popular open-source platforms for developing blockchain applications?

The candidate should name some popular open-source blockchain platforms, such as:

- Ethereum

- Hyperledger

- Fabric

- Corda

- Quorum

  • What is the concept of decentralization?

Decentralization is when a system distributes authority and power held by a central authority. Blockchain technology uses this concept by eliminating the need for a central authority. It allows users to interact directly without relying on intermediaries.

  • How does blockchain technology work without a central authority?

The candidate should explain that blockchain works by using distributed computing power to create a secure, immutable ledger that is resistant to malicious actors. Blockchain technology does not require a central authority, as it relies on consensus algorithms to validate transaction data.

Behavioral Blockchain Interview Questions

  • When looking for a job, what matters the most to you?

The candidate should explain that they are looking for a role where they can use their blockchain expertise to make a difference. They should also mention that they are looking for a team or organization that shares the same values and a commitment to blockchain technology.

  • What are your expectations from this opportunity?

The candidate should explain that they are looking for an opportunity to continue learning about blockchain. They should also mention that they want to put their knowledge into practice in a professional setting.

  • Are you comfortable working in a fast-paced, dynamic environment?

The candidate should say that they thrive when presented with challenges. They should also mention that they are able to quickly adapt to changes and take initiative in solving problems.

Intermediate-Level Blockchain Interview Questions

At the intermediate level, you will be testing the candidate's in-depth knowledge of blockchain and its components. These questions are perfect for a candidate who has a solid understanding of blockchain and is looking to get into more advanced roles.

Technical Blockchain Developer Interview Questions

  • What is a fork in blockchain?

A fork in blockchain occurs when changes take place in the underlying blockchain protocol. This then results in two versions of the blockchain. The blockchain can either be a hard fork or a soft fork. A hard fork is a permanent change to the protocol that requires every node to upgrade. A soft fork is a temporary change that does not require every node to upgrade.

  • What is the purpose of mining in blockchain?

Mining validates blockchain transaction data and secures the blockchain network. Miners get rewarded with cryptocurrency for their work.

  • What is a blockchain oracle?

A blockchain oracle is an off-chain service that provides real-world data to blockchain platforms. Blockchain oracles trigger smart contracts under certain conditions, and they also facilitate payments.

  • Which cryptographic algorithms are the most commonly used in blockchain?

The candidate should mention cryptographic algorithms such as:

- SHA-256

- Ethash


- Triple DES

- Blowfish

- Twofish

  • What is a smart contract?

The candidate should say that a smart contract is an agreement between two parties written in code and stored on the blockchain. Smart contracts can automate transactions, reduce costs, and ensure trust between parties.

  • What are some popular consensus algorithms?

The candidate should mention some consensus algorithms such as:

- Proof of work (PoW)

- Proof of stake (PoS)

- Delegated proof of stake (DPoS)

- Byzantine fault tolerance (BFT)

- Practical Byzantine fault tolerance (PBFT)

  • What is proof of work vs. proof of stake?

Proof of work (PoW) is a consensus algorithm that requires miners to solve complex mathematical equations to validate transactions. Proof of stake (PoS) is a consensus algorithm that requires users to stake their coins to validate transactions and earn rewards. PoW consumes more energy and is less secure than PoS.

  • What is a 51 percent attack?

The candidate should explain that a 51 percent attack occurs when someone or a group of people controls more than 51 percent of the network hash rate. This allows them to gain control over transactions and manipulate the blockchain ledger. It is an attack that can double-spend coins or disrupt the network.

Behavioral Blockchain Developer Interview Questions

  • What blockchain projects have you worked on in the past?

The candidate should mention any blockchain projects they have worked on in the past. They should also explain their role and responsibilities. They should also highlight any achievements or successes they had while working on the project.

  • What skills and experience do you have that make you a good blockchain developer?

The candidate can say they possess technical skills such as coding and development. They can also mention soft skills, such as communication and problem-solving.

  • How do you keep up with the latest blockchain developments?

The candidate can mention resources such as industry blogs, conferences, and blockchain forums. They should also mention any blockchain-related projects they have worked on in the past.

Expert-Level Blockchain Engineer Interview Questions

At this level, you're looking to test the candidate’s knowledge of blockchain beyond just the basics. These blockchain interview questions are perfect for a blockchain engineer who is looking to work in a more advanced role such as a blockchain architect.

Technical Blockchain Engineer Interview Questions

  • How well do you understand executive accounting? Does blockchain support it?

The candidate should say that executive accounting is a form of double-entry bookkeeping, and blockchain technology supports it. Blockchain allows for accurate and immutable record-keeping, which can help reduce accounting errors.

  • What is sharding, and how does it work?

The candidate should explain that sharding is a way of partitioning blockchain data structures so that multiple nodes can process the data in parallel. This increases the speed and scalability of the blockchain network, allowing for processing of more transactions in a shorter amount of time.

  • What is secret sharing, and how does it secure blockchain data?

The candidate should explain that secret sharing is a method of distributing secure data among multiple parties. In blockchain, secret sharing stores sensitive information such as private keys off-chain to protect it from malicious actors.

  • What are the steps involved in the blockchain project's implementation?

The candidate should explain the steps involved in blockchain  project implementation, which include:

- Requirement identification

- Network setup

- Blockchain platform selection

- Blockchain application development

- Blockchain testing and validation

- Deployment

- Monitoring and maintenance

Behavioral Blockchain Engineer Interview Questions

  • Have you ever mentored junior blockchain developers?

This question will test the candidate’s ability to lead, manage, and mentor junior blockchain developers. The candidate should explain their experience in mentoring blockchain developers, including any successes or accomplishments they have achieved.

  • How do you go about delegating tasks?

This question will test the candidate’s ability to delegate tasks effectively. The candidate should explain their approach to delegating tasks, such as breaking tasks down into manageable chunks and assigning them to people with the right skills.

  • How do you handle disagreements between team members?

This question will test the candidate’s ability to manage conflict professionally and efficiently. The candidate should explain their approach to handling disagreements, such as listening to both sides and finding a compromise.

Hire Blockchain Developers

Hiring blockchain developers can be a difficult and time-consuming process. This is because blockchain technology is still relatively new. Moreover, few people have the necessary skills and experience to work in this field. Therefore, asking carefully chosen blockchain interview questions can help you weed out unsuitable candidates and identify the top blockchain professionals.

At Revelo, we have a global network of experienced blockchain developers who can help you with your blockchain projects. We pre-vet each candidate to ensure they have the right skills and experience. Moreover, our experienced recruiters can help you find the perfect blockchain developer for your team.

Talk to us today to learn more about our blockchain development talent pool.

Further Resource: Alternative Technology Staff Augmentation

Why Choose Revelo?

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pre-vetted developers

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Juliana B.
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7 years
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