CodeSubmit Interview Series

The 9 Best Ethereum Developer Interview Questions in 2023

Want to hire your next Ethereum developer? You’re in the right place. Today, you get the 9 top Ethereum developer interview questions to use at your next interview. Want to learn more? Read on!

Interviewing Ethereum developers  

Ethereum is an open-source blockchain platform that can be used to develop various applications. Ethereum is flexible and secure, while providing enterprise-grade features. 

Ethereum developers need various skills. First, they need to understand Ethereum development, including smart contracts, transactions, consensus algorithms, sharding, and token standards. They also need to have a good grasp of cryptography including public key encryption, private key encryption, digital signatures, hash functions, and key exchange or agreement. 

Plus, Ethereum developers need to know one or more languages, depending on your needs. The most popular languages include Python, Ruby, JavaScript, Java, C++, Go, .NET, and Rust. They also need to understand frontend and backend development, including request handling, API handling, and GUI creation for dApps. 

So, how do you identify the best developers? That’s what we’ll look at now. 

Beginner Ethereum developer interview questions

What are the top Ethereum developer interview questions? 

These questions are all about identifying candidates who understand Ethereum and the possibilities the technology offers. 

1. What is the Ethereum network?


Ethereum is an open-source blockchain platform. This second-generation distributed ledger technology builds on the Bitcoin network. It’s also an operating system with features such as virtual machines, smart contracts, and transaction-based state transitions. 

2. Describe how Ethereum works. 


A blockchain is a decentralized and distributed public ledger. It verifies and records all transactions. Ethereum, again, is based on a blockchain network. Everyone on the Ethereum network has an identical copy of the ledger, so they can inspect all transactions. Ethereum isn’t maintained by a single entity, but by all the distributed ledger owners. 

In the Ethereum system, tokens are known as Ether (ETH). They can be used to buy and sell goods and services. 

3. What are the three types of Ethereum blockchain networks?


The three types of Ethereum networks are: 

1) Main network

The main network of the Ethereum blockchain network. All transactions require Ether (ETH) as it’s the native cryptocurrency on the network. Ethereum smart contracts are deployed on this network, which is also called mainnet. 

2) Test networks

Ethereum test networks for testing smart contracts that allow testing without the need to spend ETH. 

3) Private Ethereum networks

Organizations can also implement a private network. These can be run on their on-premise infrastructure or deployed on their preferred cloud platforms.

4. Describe smart contracts on the Ethereum blockchain. 


Ethereum enables users to create applications with the Ethereum Virtual Machine (EVM). This is a runtime environment for smart contracts on Ethereum. Smart contracts are essentially pieces of code. They are open-source, they contain “if-else-then” statements (to channelize the control of the program based on predefined conditions), and they are autonomous (they execute automatically when trigger conditions are met). Plus, they allow users to transfer cryptographic tokens to other users.

Smart contracts are stored on a blockchain. They can’t be modified after they’ve been deployed. 

5. What’s the difference between Ethereum and Bitcoin? 


Bitcoin is a first-generation blockchain technology that sets the foundation of decentralized ledgers. Ethereum builds on Bitcoin and offers a more scalable and programmable solution. Ethereum offers smart contracts and the ability to use distributed apps (dApps). 

Advanced Ethereum developer interview questions

Now you know what the best junior Ethereum developer interview questions are. But what questions should you ask more senior Ethereum developers? That’s what we’ll look at next. 

6. Why are Ethereum, Bitcoin, and other public blockchain networks incorruptible? 


Public blockchain networks like Ethereum are decentralized P2P networks, which means that they don’t have a central administrator. All nodes have the same authority and one user can’t override the others. 

Also, they are distributed ledgers and the nodes have transaction records; even if one node is shut down, the other nodes are available. And public blockchain networks are transparent. Miners can see all activities, making manipulation hard.

Plus, the validation process in the networks uses the “Proof of Work” consensus algorithm. Miners need to create new blocks with the transactions they validate and, to do that, solve a difficult cryptographic puzzle. They’d need to get most of the miners on board, which is unlikely to happen. 

And finally, to manipulate an existing block, the data must be changed in a transparent environment and the hash needs to be changed to avoid anomalies. The subsequent block references the previous block, so hackers would need to change the subsequent block to avoid anomalies. This is impractical in a transparent environment. 

7. What are dApps? 


Decentralized Applications or dApps are digital applications. They run on a blockchain or P2P network of computers and offer features like open source. dApps are outside of the control of a single authority and they are developed for various reasons, including gaming and finance. 

8. What factors does gas usage depend on in transactions and how is the transaction fee calculated? 


Gas usage depends on the amount of storage and the instructions in the smart contract. The transaction fee can be calculated with the formula:

Ether = Tx Fees = Gas limit * Gas price 

9. What is a state channel?


With state channels, Ethereum blockchain can be scaled. Micropayment costs and delays can also be reduced by moving on-chain components off-chain. State channel participants pass cryptographically signed messages without publishing them to the main chain until they decide to close the channel. 

Over to you!

That’s it! Those are the top Ethereum developer interview questions. 

But while these questions will help you identify candidates who understand Ethereum and know how to develop Ethereum applications, you also need to assess their skills.

And that’s what our Ethereum assessment tests can help you with. 

Try our industry-leading coding tests for free (no credit card required).