Are you ready to answer tough questions in an interview to work at the forefront of blockchain?
What skills and qualities are interviewers looking for in developers?

What questions can you expect?

How should you answer these questions?

In this guide, we will provide you with sample questions and answers to help you become a qualified blockchain developer.

FINTECH

Common blockchain developer interview questions:

1. Are you familiar with the concept of blockchain?

2. What are the different types of blockchain?

3. How would you describe the blockchain network?

4. What's the difference between public and private blockchains?

5. Provide an example of a blockchain use case.

6. If you were building a blockchain from scratch, what would be the first thing you would do?

7. What would you do if you found a security flaw in the blockchain code?

8. How well do you understand cryptography?

9. Do you have any experience with smart contracts?

10. When will you use a private blockchain instead of a public one?

11. We want to use our blockchain to collect data. What types of data will you allow users to submit?

12. Describe your experience with programming languages and software used for blockchain development.

13. What makes you perfect for this role?

14. What programming languages do you think blockchain developers need to know the most?

15. What do you see as the future of blockchain technology?

16. How often do you update your knowledge of blockchain technology?

17. There are new developments in blockchain technology that could improve your current code. How will you decide if it's worth the time and effort to improve?

How to answer these questions,

What better way to show the interviewer what you're capable of?

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Q1 Are you familiar with the concept of blockchain?

This question is a great way for the interviewer to assess your knowledge of blockchain and how you can apply it at work.

If you're not familiar with blockchain, consider researching the concept before your interview so you can answer the question with confidence.

Example ▼

"Yes, I am very familiar with the concept of blockchain.

In fact, I've been working with blockchain technology since my first job as a developer.

A blockchain is essentially a digital ledger where transactions are recorded securely and transparently. It is decentralized, meaning that there is no central location where all information can be stored.

Instead, each node on the network owns a copy of the entire blockchain database. This makes it highly secure because no single entity controls the data."

Q2 What are the different types of blockchain?

This question is an opportunity to demonstrate your knowledge of blockchain technology.

You can answer this question by defining the different types of blockchains and the differences between them.

Example ▼

"There are three main types of blockchain, namely public blockchain, private blockchain and alliance blockchain.

Public blockchains are open source networks that anyone can access.

They have no central authority or server, so all nodes in the network must agree on a transaction before it is added to the chain. This makes them very safe because there is no single point of failure;

Private blockchains are similar to public blockchains, but closed-source. The owner has complete control over who can participate in the network;

Alliance blockchains are also similar to public blockchains, but with multiple nodes. There is a central administrator who controls who can join the network."

Q3 How do you describe blockchain networks?

This question is an opportunity to show the interviewer that you understand the basics of blockchain technology. Your answer should include a basic definition and how it differs from other types of networks.

Example ▼

"A blockchain network is a decentralized ledger in which transactions are recorded in blocks that are linked together by cryptography. Each block contains a hash pointer that is linked to the previous block, creating a chain.

This structure makes it nearly impossible for anyone to change the data in a single block without changing all subsequent blocks."

Q4 What is the difference between public blockchain and private blockchain?

This question is an opportunity to demonstrate your knowledge of blockchain and how it works. You can answer this question by defining each type of blockchain, explaining what they do, and giving examples of companies that use them.

Example ▼

"A public blockchain is a decentralized ledger into which anyone can read or write transactions. It is also called a distributed ledger because there are many nodes in the network.

The advantage of using a public blockchain is that you don't have to pay anything to access its data. However, since anyone can see the information on the blockchain, it is not suitable for storing sensitive data.

Private blockchains are similar to public blockchains, but with limited access. Only authorized users can view the data stored on them. This makes it more secure than public blockchain."

Q5 Please provide an example of a blockchain use case.

This question is a great way to test your knowledge of blockchain and how to use it in the real world. In answering this question, you should provide an example of how blockchain can benefit a business or individual.

Example ▼

"Blockchain has many uses, but one of my favorite use cases is digital tokens.

In my last role as a blockchain developer, I worked with a client who wanted to create his own digital token. We started by creating smart contracts on the Ethereum network. We then created a wallet where users can store their tokens.

Users' private keys are stored on the blockchain, so they always have access to their funds."

Q6 If you were asked to create a blockchain from scratch, what would be the first thing you would do?

This question is a great way to test your knowledge of blockchain development. It also allows you to show the interviewer how you will approach the task and what steps you will take.

Example ▼

"If I were to create a blockchain from scratch, my first step would be to identify the type of blockchain I would build. There are many different types of blockchains, so it's important to know which one is best for the project at hand.

After that, I need to decide on a consensus algorithm. This is because each algorithm has its own advantages and disadvantages, so it is important to choose the right algorithm for the job.

Next, I need to choose the programming language to code the blockchain."

Q7 What would you do if you found a security vulnerability in the blockchain code?

This question helps the interviewer determine how you handled mistakes and challenges.

Your answer should show that you are willing to take responsibility for your actions, learn from your mistakes and correct them as soon as possible.

Example ▼

"If I found a security flaw in my code, I would immediately stop all transactions on the blockchain until I could correct the problem.

Then, I analyze what caused the problem and make sure new protocols or procedures are implemented to make sure it doesn't happen again.

If I can't fix the problem immediately, I will post a notice notifying users of the situation so they know not to execute any more transactions until further notice."

Q8 How well do you understand cryptography?

This question can help the interviewer assess your knowledge of blockchain technology and how you can apply it to your work.

Use examples from past projects to demonstrate your understanding of cryptography and its importance in developing secure applications.

Example ▼

"Cryptography is an important part of my work as a blockchain developer because it allows users to access data securely.

In my last role, I worked on a project where we needed to create digital signatures for customers' websites so that they could accept online payments. We use public-private key encryption to generate a unique hash code for each transaction made through the site.

This allows us to verify the identity of the sender and ensure the integrity of the information being sent."

Q9 Do you have any experience with smart contracts?

This question will help the interviewer determine your level of expertise in blockchain technology.

If you have experience with smart contracts, describe a time when you used them to solve a problem or successfully complete a project.

If you have no experience with smart contracts, explain what you would do if you were assigned a task that required them.

Example ▼

"I used smart contracts in my previous job as a blockchain developer.

I was tasked with creating smart contracts for an e-commerce company that needed to track customer purchases and ensure they received orders on time.

Using my knowledge of blockchain development, I created a smart contract that allows customers to order products from e-commerce sites and receive them within 7 days. The system also tracks each transaction so that the company can monitor sales."

Q10 When will you use a private blockchain instead of a public one?

This question helps the interviewer assess your knowledge of blockchain technology and how you can apply it to real-world situations. Use examples from past projects or experience to show that you can use this type of blockchain effectively.

Example ▼

"In my last role, I worked on a project where we needed to create a private blockchain for our company's supply chain management system.

We used Hyperledger Fabric as the framework for the private blockchain because it is easy to set up and maintain. It also has an intuitive user interface that makes it easy for non-technical employees to understand and use.

In contrast, public blockchains are better suited for applications such as encryption platforms because they are open to everyone."

Q11 We want to use our blockchain to collect data. What types of data will you allow users to submit?

This question allows you to show what you know about the blockchain and how to use it.

You should answer this question by describing what type of data you allow users to submit, why you allow that type of data, and any security measures you take with respect to that data.

Example ▼

"I would allow users to submit sensitive information, such as social security numbers or credit card information, because I know this is a common use of blockchain.

However, I only allow them to use private chains to control who can access the data. If they are on a public chain, I make sure all data is encrypted before allowing users to submit."

Q12 Describe your experience with programming languages and software for blockchain development?

This question allows you to demonstrate your knowledge of blockchain development and how it relates to other programming languages.

You can take this opportunity to explain any experience you have with the specific language or software used in blockchain development and how that experience has helped you in your previous role.

Example ▼

"I have used Java extensively throughout my career and it is one of the most commonly used languages for blockchain development.

I also have some experience with Python, JavaScript, and C++, all of which are commonly used in blockchain development. These experiences helped me understand the similarities and differences between these languages when developing on blockchain."

Q13 What makes you a good fit for this role?

Employers ask this question to learn more about your qualifications and how you feel you would be a good fit for their company.

Before the interview, make a list of reasons why you are the best person for the job. Think about what skills you have that other candidates may not have.

Example ▼

"I am passionate about technology and I believe blockchain is the future. I think my programming background makes me an excellent choice for this role because it enables me to understand complex systems.

I also have experience working with large data sets, which is important when developing on blockchain."

Q14 Which programming languages do you think blockchain developers need to know the most?

This question allows you to demonstrate your knowledge of the blockchain industry and how it relates to programming languages.

You can list several languages that are important to blockchain developers, such as Solidity, Python, JavaScript, or C++.

Example ▼

"I feel Solidity is one of the most important programming languages for blockchain developers to know because of its use for Ethereum development. It is also an object-oriented language that uses smart contracts, making it ideal for developing decentralized applications on the Ethereum network.

Another important language I recommend is Python because it is easy to learn and has many practical applications in the blockchain industry."

Q15 What do you think is the future of blockchain technology?

This question is a great way to find out what you know about the blockchain industry and what you think about its future.

Your answer should include your thoughts on why you think blockchain technology will continue to evolve, as well as any predictions you make about the future of this innovative technology.

Example ▼

"I believe blockchain technology has a bright future because it offers many benefits over traditional data storage methods.

I predict that within five years, most businesses will be using some form of blockchain technology to securely store their data.

Ten years from now, I expect all major companies will be using blockchain technology to protect their data."

Q16 How often do you update your knowledge of blockchain technology?

This question helps the interviewer determine how committed you are to your career and whether you are likely to stay with their company for a long time.

Your answer should indicate that you are interested in learning about blockchain technology, but it is also important to mention any certifications or training you have recently completed.

Example ▼

"I'm always looking for new ways to learn more about blockchain technology.

I subscribe to several newsletters and blogs where experts discuss the latest developments in the industry. I also attend as many conferences and seminars on blockchain technology as I can.

Last year I took a course on the Solidity Programming language, which helped me understand Ethereum better."

There are new developments in Q17 blockchain technology that can improve your current code. How will you decide if an upgrade is worth the time and effort?

This question is a great way to test your ability to keep up with the latest developments in blockchain technology. It also shows that you are willing to learn and adapt as new information becomes available.

Example ▼

"I first look at how much time it will take to upgrade my code, which can range from a few hours to a few days depending on the size of the project.

I then compare this to the time it takes to implement new development in the current code. If the difference between the two is big enough, I'll definitely consider upgrading my code."