10 Software Engineer Interview Questions to Help You Hire the Right Developer


Whether it’s in-house or freelance, finding the right software engineer takes some work, and it's even more difficult if you're unsure of what to ask. Software developers are technical people, so most interviewers tend to jump into the technical interview right away, but there are plenty of personality and ethics questions that you can ask to ensure the one you hire is the best fit for your project.

In this post, we'll walk you through the interviewing and hiring process.

Preparing for the Interview

As with any interview, you need to know what you plan to ask before you start. Although the questions will depend on your software project, here are some general steps for your preparation:

1. Know your project requirements

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You need a software engineer that understands your needs. The only way for the developer to understand what you need is for you to have clear project specifications in mind before the interview. If you already have project documentation, review it and identify important components.

2. Know your budget

Every software developer has their own rate. Most of the time, years of experience, tech stack, location, and project complexity determine what you'll pay a developer. According to our study of app costs, an iOS developer in North America has a median rate $150/hr, whereas it is $11/hr in Indonesia.

There is no need to interview a software engineer that is outside of your budget, so understand your budget constraints before you start an interview.

Tip: If you're hiring a freelance software engineer, be sure you know your scope, budget, and design before you start interviewing developers!

3. Know your deadline

You need to set a realistic deadline, and a software developer will give you a general estimate based on project requirements. Some developers don't work well under pressure, so knowing your timeline and asking a developer for a time estimate helps identity the right candidate.

4. Prepare your questions

Some interviewers ad-lib their questions, and many times the interview goes off course as conversation continues. Prepare to ask the developer questions that relate to both their technical and soft skills.

Software Engineer Hiring Process

There are three main interview phases when working with any type of app or software developer. You may do only one or all of the following:

  • Phase I: This is the basic introduction phase and usually involves basic questions about previous employment and any previous projects the software developer has worked on.

  • Phase II: This is the technical stage of the interview. If you're not a technical person, you might have another developer or project manager familiar with development ask these questions to evaluate the developer's skill. Usually, they result in pseudo-code or logic skills that show whether or not the developer understands the question.

  • Phase III: This is the final part of the interview where the developer can ask questions and clarify any confusion.

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Interview Questions to Ask a Software Engineer

Once you have a shortlist of software engineer candidates, below are the essential questions to ask them. Keep in mind that these questions are general software development questions that don't refer to any specific language. Not only do they test the developer's knowledge of engineering and building software, these questions will help you understand whether or not the developer can communicate effectively with you.

1. Discuss one of your previous projects and explain how you completed it successfully.

This question allows the engineer to openly discuss their previous project without getting too technical. There are several advantages with this discussion. The first one is that you can identify if the candidate worked with a team and if he or she was able to work together to brainstorm solutions. It also helps you understand their management skills, time estimates, interactions with project managers, and their contribution to the overall project.

2. Did you run into any obstacles with your project and how did you handle the issue?

This is an important question, because it identifies how the candidate deals with obstacles, delays, and any problems that come up during the project. Most software development projects have hurdles of some kind, so a developer that has troubles identifying an obstacle with their previous project may raise a potential red flag. If you decide to hire a software developer, you need to know how they are able to overcome problems to get the job done and within the deadline.

3. Do you follow the Agile software development process?

Today, Agile is the most common way to manage software development procedures. Software developers should be on board and familiar with the process, so you can ask them if they are willing to work under those circumstances.

Learn more about Agile development here.

4. What do you know about multi-threading?

Multi-threading is a way to improve the performance of an application. Multi-threading is a process that uses several processors to run snippets of code. It improves performance and stops code from "hanging" when it runs.

5. What are your thoughts on unit testing?

Unit testing and test driven development (TDD) are often regarded as best practices in software development and code maintenance. Unit testing is an extra set of code that tests various methods and procedures for logic errors and coding flaws. This helps eliminate many of the bugs that could be promoted to production.

Every developer should be familiar with unit testing, and it’s important to know how much a software developer prioritizes it in their workflow.

6. What is MVC?

MVC stands for Model-View-Controller. It's a way to separate code into its own compartments, like so:
Controller holds the business logic
View is the front-end presentation layer
Model holds the data that is passed to the controller, which then passes it to the View.

7. How familiar are you with OOP analysis and design?

Object-oriented programming (OOP) is the core of major languages such as VB, Java, C++, and C#, so top software developers should have strong OOP skills. OOP is a process of using classes to describe components of a program. For instance, if your program explains a house, classes would be the roof, doors, windows, and rooms. Your programmer should be able to explain classes using a similar analogy.

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8. How do you organize your class modules and assets?

This will help you understand how the candidate organizes their code. There is no one "right" way to answer this question, but your team probably has a set standard and it helps to know if the developer organizes code in a way that is easily maintained and can be further documented.

9. What do you know about ORM?

Object-relational mapping (ORM) is a way to use software code so it can map to database tables. This technique turns tables into their own classes, so then developers can use those classes for LINQ queries. The candidate might mention Hibernate, which is one of the most common ORM frameworks.

10. What is your process for finding a bug in an application? How much time do you typically spend on debugging?

The first question tests the way the candidate thinks when working with difficult bugs. Every candidate has their own process, but they must use a debugging tool, understand how to sift through each line of code using that tool, and then understand what must be done to fix the bug without affecting other code within a project.

The second question helps gauge how often a developer needs to debug his or her own code. Developers that need to spend a vast amount of their development time debugging may be ones who need extra help improving the code that they write.

Wrapping up the Software Engineer Interview

Once the more general questions are out of the way, you can then ask the software engineer some follow-up questions that are specific to the tech stack or programming languages/frameworks that your project requires (e.g. React.js, PHP, Ruby on Rails, Java, etc.).

Before you end the interview, remember to ask the candidate if he or she has any questions, as they should have several regarding your business, the specifications of the project, the team, and more. If possible, try to keep a record of their answers, and be sure to follow-up with any engineers that you are interested in hiring after your interviews.

Hiring top software developers can be an arduoous task, especially if you’re spending time vetting inexperienced candidates, unqualified developers, or just not sure where to look. Learn more about CodementorX and let us know what type of engineers you’d like to hire.

Have any software engineer interview questions that you'd like to add? Let us know in the comments below!

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