20 Interview Questions to Ask a Blockchain Developer

You’ve found your candidates, now what?

When hiring a blockchain developer, interview questions are the best way to gauge their competency and abilities. Trust me, we’ve suffered the consequences of a less-than-thorough interview process.

Don’t make the same mistakes we did. Use these 20 interview questions to find the best blockchain developer.

General Questions for a Blockchain Developer

Here are a few general questions to kick things off.

1. Why are you interested in this position at our company?

This question allows you to gauge whether they’ve done their research to know who they’re working with.

2. What industries do you specialize in?

Blockchain tasks are often very industry-specific. If you need a blockchain developer to handle development for your cryptocurrency business, for instance, finance experience is a must.

3. What were your responsibilities in your previous role?

Gain more insight into what specific capabilities this blockchain developer has. Were they responsible for developing smart contracts? Did they work on core blockchain development or blockchain software development?

4. How do you explain blockchain to someone who doesn’t know anything about it?

Blockchain developers are specialists in a very specific niche. When they’re working on development teams or with non-technical people, they should be able to give their peers a basic description of what they do.

5. What is meant by “Blocks” in blockchain?

This goes hand-in-hand with the previous question. They should be able to explain “blocks” in plain terms that non-tech people can understand.

6. What is cryptography and how does it relate to blockchain?

Cryptography is what makes blockchain secure, so a blockchain developer should be able to explain the relationship between the two.

7. Name the different types of blockchain networks.

Blockchain developers should be able to name and describe private, public, consortium, or cooperative blockchain.

Technical Questions for Blockchain Developer Interviews

Blockchain developers need a lot of technical knowledge.

These questions can help you make sure your developer has the experience and knowledge necessary to do their job well.

8. What is a smart contract and what are some of its applications?

Smart contracts are a huge part of blockchain developers’ responsibilities, so a blockchain developer should be able to explain how one works.

9. What is Ethereum and how many Ethereum networks are you familiar with?

Ethereum has multiple networks that a good blockchain developer should be familiar with. This question can gauge the breadth of their experience with the popular platform.

10. What is the difference between Proof of Work and Proof of Stake?

This question helps you test the developer’s understanding of consensus mechanisms, which is essential to blockchain development.

11. How do you approach testing in blockchain development?

Testing is an essential part of the blockchain development process, so developers should have a clear plan in place on how to conduct this testing.

12. How do you ensure data integrity and privacy in a blockchain application?

Data integrity and the protection of sensitive data is a huge part of why blockchain is used in the first place, so a blockchain developer should be able to describe how exactly they maintain privacy and data integrity in a blockchain application.

13. What is mining?

This helps you see how much the developer understands blockchain fundamentals and how blockchain systems operate.

14. What is a trapdoor function and why is it important?

This question helps you test the developer's knowledge of cryptographic functions crucial for blockchain security. Understanding trapdoors shows that a developer understands how to maintain data integrity and security.

Scenario & Experience-Based Questions for Blockchain Developer Interviews

There’s knowledge and then there’s experience. Your blockchain developer should have both.

These questions can help you gain a greater understanding of a blockchain developer’s practical knowledge and how they would handle certain situations at work.

15. Describe a challenging blockchain project you worked on. What was the challenge, and how did you overcome it?

This is a great opportunity for the blockchain developer to explain how they were able to find solutions during a challenging project.

16. Have you ever dealt with a security vulnerability in a blockchain application? How did you handle it?

Even in a secure environment, things can go wrong. This question helps you understand how a blockchain developer keeps data secure if a vulnerability occurs.

17. Have you contributed to any open-source blockchain projects? What was your role and contribution?

A blockchain developer who contributes their time to an open-source project shows that they are passionate about what they do.

18. Have you ever encountered a fork in a blockchain project? How did you handle the situation?

Forks are a common situation that blockchain developers find themselves having to deal with, so they must know how to navigate these.

19. Describe a situation where you had to balance speed and cost while executing transactions on a blockchain. How did you manage it?

This helps you identify if they can optimize both transaction speed and cost.

20. Tell us about a time when you had to explain a complex blockchain concept to a non-technical stakeholder. How did you approach it?

This helps you gauge their communication skills and ability to interact with non-technical people in a team setting.

Best Place to Find Blockchain Developers

If you’re looking for a vetted, talented Blockchain developer, we recommend Toptal.

Their rigorous screening process only accepts the top 3% of freelance talent that applies, so you know for sure that your blockchain developer has loads of experience and is up for the job.

Frequently Asked Questions

What questions to ask about blockchain?

In an interview, you should ask questions like “what is blockchain,” “what are the individual blocks in blockchain,” and “what is cryptography,” among others.

What are the interview questions to ask Blockchain developers?

Interview questions for blockchain include “what is blockchain,” “what are the individual block in blockchain,” and other questions like “why are you interested in a position at our company,” and scenario-based questions like “Have you ever dealt with a security vulnerability in a blockchain application? How did you handle it?”

How do I prepare for a Blockchain developer interview?

To prepare for a blockchain developer interview, review your skills and be ready to discuss your experience and scenarios in which you have solved blockchain-related problems.

What are the 6 must-have blockchain developer skills?

Blockchain developers need skills like proficiency in programming languages (C, C++, Solidity, Golang, HTML, etc) and data frameworks (Hadoop, etc) as well as data structures like Merkel tree and Patricia Tree.

Which blockchain has the most developers?

Over 54% of blockchain developers are working on the Ethereum blockchain.