DoorDash Software Engineer Interview Questions & Answers
Below is a list of our Doordash interview questions. Click on any interview question to view our answer advice and answer examples. You may view 5 answer examples before our paywall loads. Afterwards, you'll be asked to upgrade to view the rest of our answers.
Behavioral
1. If hired by Doordash, can you estimate what portion of your day will involve coding and other activities you will perform when not coding?
How to Answer
This operational question is seeking to understand how you go about doing your job on a day-to-day basis. Operational questions will ask you about the processes you use to accomplish the tasks required by this position. The best way to answer operational questions is directly and briefly. The Doordash interviewer will ask you a follow-up question if they need more information or want to explore the topic in more detail.
Answer Example
"During a normal day, I spend about 60% of my time writing code. The remainder of the day is spent reviewing my work, meeting with my manager, collaborating with other coders on my team, and learning new coding technologies and methodologies."
Anonymous Interview Answers with Professional Feedback
Anonymous Answer
Jaymie's Feedback
Behavioral
2. Walk me through your process for designing scalable applications.
How to Answer
A Doordash interviewer will ask this type of question to understand how you go about doing your job. When asked to walk somebody through the process you use, you should divide it into several distinct steps and briefly describe each one. Be careful not to talk too much or overcomplicate your answer. If the interviewer needs more details, they will request them.
Answer Example
"The process I use for designing scalable applications begins with minimizing the code I use. I focus on the application's functional and non-functional requirements and then create code that satisfies those. I break the application down into distinct processes and code each one sequentially. The final step is to test the application and debug it."
Behavioral
3. Describe the process you use to create a program, from requirements definition to delivery.
How to Answer
When the interviewer asks you to describe a process, they are seeking to understand how you go about doing your job. When preparing for these questions, you should review the job description to fully understand the position's requirements and how the organization will expect you to do your job. You should also review the processes you currently use to ensure they align with this role's requirements. Your answer should describe each step of the process in a sequential manner. Make sure to keep your response simple and to the point.
Answer Example
"The process I use to create a program begins with gaining a thorough understanding of the requirements for the application. Once I understand these, I create a flow diagram for how I believe the application should work. I then create code for each operation within the application. I submit the final program to the quality control team, which reviews and debugs the program. The final step is to get sign-off from the users. Throughout the process, I document my work so that it can be replicated or updated if needed."
Behavioral
4. How do you go about addressing errors in your code?
How to Answer
Nobody is perfect, even the highly skilled software engineers Doordash hires. Every software engineer has errors in the code they create. Denying this will be a red flag, which will make the interviewer skeptical of your qualifications. A better approach to answering this question is to acknowledge that you make errors and have a process you use to identify and correct them.
Answer Example
"After I create a segment of code, I take several steps to identify any errors and debug them. These include wrapping the code, using try/catch statements, and using various debugging tools. Once the entire program has been completed, I ask either my peers or the quality control team to review the code and identify any errors I may have missed."
Behavioral
5. What process do you use to test and find bugs in an application you've developed?
How to Answer
The Doordash interviewer will likely ask a series of questions regarding your process because they seek to understand the steps you generally take in scenarios such as this one. As an experienced software engineer, you should be able to easily describe the procedures you use to test and debug the application you develop. Since this is an operational question, your answer should be direct and to the point. You should anticipate additional follow-up questions.
Answer Example
"Since I typically use the agile or waterfall development processes, just as you do here at Doordash, I test my application at various stages during the development process. This allows me to correct errors before they have greater implications later in the process. I use a variety of tools to test and debug the software. I also ask my peers to review my work during the development stage. Once the application is completed, I send it to the quality assurance team for final testing and debugging."
Behavioral
6. How would you implement Dijkstra's Shortest Path using a programming language with which you are familiar?
How to Answer
When asked about how you would implement a procedure or perform an operation, the interviewer hopes to learn more about how you go about doing the job for which you are interviewing. This is known as an operational question. When answering an operational question, you should step the interviewer through the process briefly and directly. It may help break the process down into smaller steps to help the interviewer better understand your methodology. You should be prepared for follow-up questions any time you answer an operational question.
Answer Example
"When programming in Ruby, I would implement Dijkstra's Shortest Path by creating an algorithm to identify the shortest path between two nodes which have positive-edge weights within the graph. I would first query my libraries to see if I have done this before or if another developer had already created a similar algorithm. If not, I would follow the guidelines within Ruby to accomplish this."
Behavioral
7. How do you go about organizing CSS files, and why do you prefer this approach?
How to Answer
This is an example of an operational question that has technical aspects to it. The interviewer is interested in learning more about how you go about doing your job related to this specific topic. No two interviewers are the same, so the questions you will be asked may vary from interview to interview. The best way to prepare for this is to research the company, review your resume, and spend some time reviewing the operations you perform and the technologies with which you work.
Answer Example
"The method I use to organize my CSS files is based on the file's style type. Categories I use include reset, layouts, list, carousel, tables, and several others. This enables me to quickly locate the specific style I'm looking to incorporate into the front end of my program."
Behavioral
8. Which do you prefer - a micro-service approach or a monolithic app?
How to Answer
When asking about a preference, the interviewer is seeking to understand how you approach your work. Your response to this question is based on two factors. The first is your experience and skill set in this job. The second is the research you have done about Doordash and your understanding of their preferences for the type of operations they perform. Your answer can either align with Doordash's processes or conflict with them. If you choose to conflict with them, you should rationalize your answer based on your experience.
Answer Example
"While I'm aware that Doordash prefers monolithic applications, I use a micro-service approach. I like to do this because it allows me to create different services that operate independently and, therefore, more robustly. While this approach results in better performance and more efficient code, it also creates multiple failure points. Extensive testing before putting the application into production can usually mitigate this."
Behavioral
9. What do you look for or check when reviewing another team member's code?
How to Answer
This is a hybrid question, which has elements of both operational and technical questions. Since both operational and technical questions are responded to directly and succinctly, your answer will be the same. This question's broad nature also indicates that the interviewer will likely ask a follow-up question regardless of how you respond to their original question.
Answer Example
"When I'm asked to review another team member's code, the first thing I look for is to make sure that the code is efficient and follows our organization's guidelines. I'm careful not to personalize my review or make recommendations on improving the code based on my personal preferences and coding style. I also strive to impart new knowledge to the coder when I make suggestions. An example of this would be showing them a more efficient way to accomplish the task, which they may not have considered."
Communication
10. How would you go about explaining cloud computing to someone at Doordash that doesn't have a technical background?
How to Answer
The purpose of this question is to gain an understanding of your communication skills. Throughout the interview, the Doordash hiring manager will seek to understand some of the soft skills you have pertaining to this job. These include communication, teamwork, conflict resolution, and others. Every time you answer a question, you are being evaluated for both your experience and skills, as well as your ability to communicate. This question relates directly to this objective.
Answer Example
"The easiest way to understand the cloud is that it is just another computer, phone, or storage device which is located remotely. It is similar to your hard drive or USB drives, except you access it via the Internet instead of directly on your Doordash computer. The cloud can also host applications and execute them remotely. Again, this is similar to your computer, cell phone, or any other device you may use. Whenever you make a phone call, ask Google for information, or order something on Amazon, you are using the cloud."
Compatibility
11. Doordash is very proud of their products and the people who develop them. In your opinion, what distinguishes a great software engineer from an average one?
How to Answer
When an interviewer asks this type of question, they seek to understand your perception of excellence in this role. When answering the question, you should align your response with the job requirements, as defined in the job posting. You can also incorporate your past performance to demonstrate that you are aware of what excellence is and strive to achieve it.
Answer Example
"I believe the trait which distinguishes a great software engineer from an average one is being able to balance excellence and performance. While I strive to write perfect code, I recognize that the project has a deadline and needs to be accomplished on time and under budget. If I have to compromise the quality of my code, it is done in such a way that it will not impact the final performance of the product."
Competency
12. Which design patterns do you use, and in what situations do you use them?
How to Answer
This is an operational question. Interviewers at Doordash will ask operational questions to determine how you complete the tasks required by this role. Operational questions are best responded to succinctly and directly, with little embellishment. Additionally, you should always expect follow-up questions when an interviewer is asking about a specific task.
Answer Example
"During my software development career, I've tried many different design patterns. These include Singleton, MVC, and Template. However, the one I prefer and use most often is Iterator. This helps me code in an organized fashion and reduces the amount of time to develop the software. It also results in fewer errors and less debugging."
Competency
13. Please describe a stack and the two operations it performs.
How to Answer
When the Doordash interviewer asks you to describe something, you should immediately identify the question as being technical. When responding to a technical question, you first define the term or concept and then explain how it is used in the work you are performing. If the interviewer asks you follow-up questions, they are expressing a strong interest in this topic and indicating that it is vital to their operations. This signals you to expand on your answer and give them more details than you normally would.
Answer Example
"A stack is a data structure that has several distinct characteristics. Stacks use a LIFO process, organizing the data as last in, first out. This differs from a queue, which processes data as first-in, first-out. The two operations a stack performs are push, which is the insertion of the data at the top of the stack, and pop, which is the removal of the last item added to the stack."
Competency
14. What are the differences between blocking and non-blocking calls in the context of Node.js?
How to Answer
During an interview as a software engineer, you can anticipate that most questions will be technical or operational. The best way to prepare for this type of interview is to first research the company to understand their programming and the products they produce. Next, you should carefully review the processes you use as a software engineer to develop programs. Having a clear understanding of these will help you respond to any question the interviewer may ask.
Answer Example
"Blocking calls require that the program waits until a non-JavaScript operation is completed before additional JavaScript commands can be executed. Non-blocking calls can execute commands asynchronously at any time. This characteristic results in non-blocking calls having a performance advantage. Node.js uses both of these types of calls."
Competency
15. Doordash web developers are incorporating HTML5 in their most recent websites. Can you describe the functions of web workers in HTML5?
How to Answer
During an interview as a software engineer, you can anticipate that most questions will be technical or operational. The best way to prepare for this type of interview is to first research the company to understand their programming and the products they produce. Next, you should carefully review the processes you use as a software engineer to develop programs. Having a clear understanding of these will help you respond to any question the interviewer may ask.
Answer Example
"While JavaScript is widely used when creating websites, it has its limitations. The language is single-threaded; therefore, concurrent or simultaneous operations are difficult to program. Web workers in HTML5 allow programmers to create scripts that run in the background and are invisible to the users. This is a workaround to executing multi-threaded application operations within JavaScript."
Competency
16. Can you define black box testing and white box testing and discuss the differences between them?
How to Answer
Often during an interview, you are asked to define two terms used in the job and contrast them. This is an example of that type of question. When practicing interview questions, you'll note that your response is typically structured in a specific way. This makes responding to questions during the interview easier because you don't have to think about how to structure your answer. In this case, you want to first define each term and then describe the differences between them. You may also want to provide an example of how the concepts are used and the work you do.
Answer Example
"There are two major types of software testing. These include black box and white box. Black box testing is done without the tester knowing anything about how the application was created. On the other hand, white box testing is done by somebody intimately familiar with the structure and content of the application. White box testing allows the tester to examine the code and modify it to fix any discovered issues. Black box testing is typically used to simulate how the user views and interacts with the application."
Competency
17. In your opinion, what is the difference between computer software and a computer program?
How to Answer
A Doordash interviewer will ask this type of question to explore your knowledge, skills, experience, and qualifications for this job. Knowing the distinction between these two standard terms is not that difficult but will indicate that you are a viable candidate and convince the interviewer to proceed with the interview.
Answer Example
"Many people confuse these two terms. I define them as a computer program that is a set of code that executes specific tasks. Computer Software, on the other hand, is an application that performs a function for the end-user. Computer Software contains computer programs. Computer Software is more user-centric, whereas computer programs are more machine-centric. Is this the same way you use these terms here at Doordash?"
Competency
18. What do you feel are the critical principles of good software engineering?
How to Answer
This is a general question that asks you to characterize what makes a software program efficient and effective. Your ability to do this will help the interviewer at Doordash understand your qualifications for the position. Your answer should incorporate both the requirements for the job, as stated in the job description, and your previous experience writing code. You should limit your response to two or three critical principles and anticipate a follow-up question from the interviewer.
Answer Example
"There are several critical principles I try to incorporate in any code I write. These include simplicity, standardization, and ease of understanding. By doing this, I ensure that the code is effective and easy to understand and update, if necessary. I also document my code so that other programmers can comprehend it and modify it if required. Are these the same practices you employ here at Doordash?"
Competency
19. Can you describe what you know about object-oriented programming?
How to Answer
This is a technical question asking you about one of the types of programming disciplines. The other is Functional Programming. Knowing the differences between these two approaches and their benefits is critical for an experienced software developer. A Doordash interviewer will ask you technical questions to probe your knowledge, experience, and qualifications for this position. Technical questions are easily answered by defining the term you are being asked about and then discussing its features and benefits. You can also provide an example of how it is used to illustrate your answer.
Answer Example
"I use Object-Oriented Programming, also known as OOP, quite a bit. My definition of this is that it is the type of programming in which you define the data structure and the types of operations that can be applied to the data. The benefit of this approach is that it helps you logically organize code around a specific parameter. It also makes code easier to be maintained and documented. Another advantage is that objects can be inherited and extended, thereby facilitating the software development life cycle. Based on my research, the software engineers here at Doordash prefer OOP as well."
Competency
20. Here at Doordash we prefer to develop software that will scale as we grow. What methodologies do you use to ensure that your program will scale?
How to Answer
Creating programs that scale is a critical skill in today's fast-changing business environment. Businesses like Doordash need appropriate applications for their current size and activity level but can grow as the business grows. Developing scalable programs saves the business money during the initial development cycle. Also, it prevents Doordash from reprograming its applications or adopting new ones when the business activity increases beyond the capability of the current program. Your answer to this question should discuss the specific techniques and methodologies you use to accomplish this objective.
Answer Example
"The first step in a software development lifecycle process is to define the requirements for an application. During this phase, I inquire with the Doordash project stakeholders about the possibility of the operation related to the program expanding or growing and the need for the program to scale. Once I confirm this need, I'd then go about developing a program with scalable features. The methodologies I use to accomplish this include using microservices instead of a monolithic architecture, assigning the appropriate caching, queues, databases, and selecting the appropriate development language and deployment platform. Languages I prefer for scalable programs include Ruby and Django if it is a web application. I'm also more inclined to develop the application to run on a cloud platform which provides the greatest flexibility and scaling."
Competency
21. What are the differences between an array and a stack?
How to Answer
This technical question is asking you to compare two concepts used in the role of a Doordash software engineer. When comparing two concepts, you should first define each of them and then discuss how they differ. It may be helpful to provide examples of how the concepts are used and the work you do to demonstrate your understanding of the subject matter.
Answer Example
"A stack is a data structure that utilizes the last in, first out principle for presenting data to the application. On the other hand, an array doesn't have a fixed structure for how data is added or retrieved by the application. A stack may be used in an application that requires the most recent data to be presented first. An array can be used to retrieve any of the data, regardless of when it was added to the application."
Competency
22. Please describe responsive design and the difference between fixed and fluid layouts.
How to Answer
You should immediately recognize this is a technical question. Technical questions ask you to define a term or concept and then discuss how it is used in your work. When responding to this question, you should be brief and to the point. The interviewer at Doordash will request additional information if they need it. You should also provide an example if possible to further demonstrate your knowledge of the subject.
Answer Example
"Responsive design refers to the process of creating web content that is formatted according to the device you are using to browse the site. It uses media queries to address breakpoints and scale images, wrap text, and adjust the layout, so the website is presented consistently across different devices. Compatible devices include computers, tablets, and mobile phones. Response designs utilize the fluid website design process. This differs from a fixed design in that it uses percentages versus fixed pixel widths."
Competency
23. Can you describe Doordash's software development life cycle as you understand it?
How to Answer
This is an example of a hybrid operational and technical question. It asks you to define a concept relative to this profession and describe how you go about doing this job. When answering these types of questions, you should be direct and to the point. The Doordash interviewer is likely to ask several follow-up questions to explore this topic in more detail. Your answer should also be aligned with the requirements for this job, as defined in the job posting.
Answer Example
"The software development life cycle, or SDLC, is a process that most developers follow to create an application or program. I understand Doordash uses individual steps that include defining the requirements, planning the development, creating the code, testing it, and deploying the application. Specific methodologies used to accomplish this include the waterfall or spiral models or the Agile framework. Is this accurate?"
Competency
24. Can you describe a tough software development problem you encountered in your last job and discuss how you solved it?
How to Answer
This is an experience-based question. Experience-based questions ask about a specific situation and seek to understand how you resolved it. This provides the Doordash interviewer with information about your background and your ability to do the job. When responding to this type of question, keep your answer simple using plain language the interviewer will likely understand.
Answer Example
"When creating an internal application to help our company's employees track their expenses, there was a bug in the program which impacted the rounding of percentages. After hours of examining the application and attempting to fix the problem, I could not identify the bug. I asked one of my peers to look at my code, and they quickly found the issue. This helped me realize that sometimes I'm too familiar with the code I write, and a fresh set of eyes can be helpful."
Competency
25. How would you accelerate the response time of a website you created for us here at Doordash?
How to Answer
When conducting an interview, hiring managers like the ones at Doordash are interested in one of three things - how you can help their organization make money, save money, or save time. The questions they ask will be specific to these objectives. You can prepare for the interview by understanding the organization's mission, the role of the job you are interviewing for, and how you can help them achieve one of these three objectives. In this case, the interviewer is seeking to understand how you can save time.
Answer Example
"There are several ways you can accelerate the response time of a website. These include using adaptive images, employing a cache, minimizing the number of plugins you use, compressing the content, and enabling HTTP to keep-alive response headers. The methods I use depend on the specific application and how the users interact with it."
Competency
26. Walk me through the steps to build a single page application with multiple sections using the programming framework in which you typically work.
How to Answer
You can often identify the type of question you're being asked by how the interviewer asks it. When you hear a phrase such as 'walk me through the steps...,' you know this is an operational question. The best way to respond to this question is to break down the process into individual steps and briefly describe each one. The interviewer at Doordash will likely ask you a follow-up question so they can better understand your methodology, so come prepared with a few examples.
Answer Example
"I generally work in Ruby, so the first thing I do when building a single page application is diagram based on the functional and non-functional requirements. I then search my libraries to see if I have code that I can apply to the application. Then, I write the code that I need to create the application according to the user specs. Finally, I test, debug, and finalize the application before publishing it. I create documentation throughout the process so other programmers can follow my steps and modify the application."
Competency
27. Many Doordash Software Engineers prefer to program in Java. Can you describe how you would implement linear search in JavaScript?
How to Answer
This question asks you to detail the process you use to perform a specific operation within a software programming language. During an interview, you should listen carefully to each question the interviewer asks. Always make sure that the interviewer completes the question before you begin to formulate your answer. This will ensure that you respond to the right question and provide the interviewer with the information they are seeking.
Answer Example
"The easiest way to implement a linear search within JavaScript is to create an algorithm that examines each element in the list and determines whether it matches the value I have defined. Once I've created the algorithm, I can repurpose it by simply redefining the value and/or the list I am using. This is just one of the Java programming techniques I will use if hired as a Software Engineer here at Doordash ."
Education
28. What are some of the programming languages you are familiar with, and which ones do you prefer?
How to Answer
This is a general question that an interviewer at Doordash will ask to determine your proficiency in programming and whether the languages you prefer are the same ones Doordash uses. During an interview, you will be asked a mix of general, operational, technical, and behavioral questions. Interviewers will ask these in random order, so you need to be prepared for each type of question.
Answer Example
"I'm familiar with many different software programming languages. These include C, C++, Java, Ruby, and Perl. My favorite is Ruby because it is easy to use, has a wide range of libraries already available, and is understood by most other programming professionals."
Experience
29. Here at Doordash, we have embraced Agile methodology. How experienced are you with the Agile software development process?
How to Answer
This question is asking about your familiarity with a specific process used in software development. It may be a follow-up question to a previous answer you provided the interviewer. When asked this type of question, you should first define the concept or topic and then explain how it is used in your job. This will demonstrate your knowledge of the subject and your experience employing it in the work you do.
Answer Example
"I am very experienced with the Agile software development process. As you know, it is a methodology used when creating a program. Its central concept is iterative development. This involves collaboration between the software development team and the organization members who will be using the application. The benefit of this is that it allows for identifying and correcting issues at each stage of the process rather than after all the work is completed."
Personal
30. Here at Doordash we value work life balance and initiative. What personal software development projects have you worked on outside of work?
How to Answer
In addition to seeking candidates who have the skills and experience necessary to perform the job, hiring managers at Doordash want to make sure the individual will fit into their organization. This is why they are likely to ask you about activities outside of the workspace and personal interests you may have. Your ability to contribute to the corporate culture is equally as important as your ability to do the job. You should have some stories about your personal life prepared if the interviewer asks about this.
Answer Example
"As odd as it sounds, I do enjoy programming and creating applications outside of work. I enjoy this because it allows me to test my skills and utilize new methods on applications I find interesting without the pressure of meeting a deadline or end-user requirements. I recently created a program that allows me to control several different Wi-Fi LTE devices in my home from my phone. The app has features similar to the Doordash console, but with a customized interface and more efficient code."