A technical interview is designed to help an organization evaluate a candidate’s knowledge of coding algorithms, data structures and common software development terms (e.g., binary trees, strings, arrays, queues, graphs, linked lists).
Although interviews of this nature do not reflect the typical day-to-day work environment of a software developer or product manager, the ability to think through problems, develop solutions, and craft plans to test and implement them are central to the profession.
Tech interviews are often the first step in the interview process. In other words, employers seeking technical candidates want to learn what a candidate can do before they learn who they are.
What traits are firms seeking in candidates?
One of the most important traits candidates must show is demonstrable coding skill. Organizations hiring for technical roles want to see that you can think through a problem, craft a response and review/test your code. Being able to articulate your design and execution process—sometimes in a self-directed, timed environment—is key.
What does the tech interview look like?
The technical industry is unique in that successful interviewing requires having specific, specialized knowledge. Organizations often assess this knowledge at the first stage of the interview process, saving questions about your interests, personality and experience for future rounds.
A technical assessment generally takes one of two forms: a timed, self-directed test or a live coding session with an interviewer. Unless the role for which you are interviewing requires knowledge of a specific programming language, you are typically free to complete the assessments in the programming language of your choice.
What types of interviews are there?
Self-directed timed test
These are typically 30-60 minutes of continuous assessment. Since you can't start and stop, plan ahead to ensure you have time set aside, a quiet place to work and that your technological needs (e.g., fully charged laptop, strong and stable internet connection) are met.
Organizations may use established platforms such as HackerRank and CodeSignal or have their own proprietary software. Your test might include following prompts on a screen or writing out code offline and uploading it within a given time period.
Submissions are not typically reviewed in real time and it may be several days or weeks for an organization to decide if you have demonstrated technical proficiency. If you pass this test, you will be contacted by a company representative for one or more interviews to talk about your thought process during the test, your general aptitude for technical problem solving, and how your personality and interests align with the organization.
Live with interviewer
Typically this is a 30-45-minute conversation (in person or virtually over video chat) with a technical interviewer asking a series of questions. Using pen and paper, markers and a whiteboard, or a video screen, you will perform calculations and write code in real time.
It is important that you talk through your thought process as you go. The primary reason interviewers conduct this type of interview is to better understand how you think, approach a problem, set up your program and determine it would work.
Some personality questions may emerge during the live technical interview, but the majority of the time will be focused on coding. In one or more subsequent interviews, the interviewer(s) will ask questions that more thoroughly assess how your personality and interests align with the organization.
What are common pitfalls to avoid in interviews?
Tendency to rush
- Slow down and think through the question first, as there may be multiple steps to follow or specific details to account for.
- Build in a process for testing your code. Even in real-world programming, no one gets it right on the first try. A skilled developer knows they have to check their work.
Fear of asking questions
- There’s likely something you don’t know or information in an interview prompt may be missing or misleading.
- Show your interviewer that you are astute and inquisitive by asking questions.
- Don’t sit in silence and panic if you’re faced with unfamiliar content. Acknowledge when what you’re looking at is new or a concept you only briefly studied in class.
- Speak with the interviewer, working through the prompt with them so they see how you process new information.
What are ways to prepare for interviews?
Resources abound (many of them free) that offer lessons and platforms for developing your own coding projects in a variety of programming languages. Popular options include:
- LinkedIn Learning: 5,000+ on-demand courses at no cost to the Princeton University community
- Udemy: Video courses on a range of topics. Search a topic like “Python programming” and use the price filter to select the ones that are free.
- FreeCodeCamp: A donor-supported tax-exempt 501(c)(3) nonprofit organization whose mission is to help people learn to code for free.
There are also several ways to collaborate on coding with classmates at Princeton:
- HackPrinceton: Meet fellow hackers from around the world, learn new skills, and work alongside seasoned mentors to collaborate and build out brilliant, innovative and impactful ideas.
- Rehack: Support the development of creative solutions that allow for greater and healthier relationships between people and technology by redesigning consumer tech products in a more meaningful, socially responsible way.
- Princeton Data Science Competition: Engage in the study and practice of data science and machine learning through Independent and collaborative data science and machine learning competitions.
Practice Tests for Technical Interviews
Entering “technical interview prep” in any search engine will yield many videos, podcasts and documents offering tips and advice. Be cautious as you explore these tools, as some are free snippets serving as advertising for paid products.
Content on sites like Quora, Reddit and Glassdoor are populated by group members and may not accurately reflect the material covered or conditions under which your interview will take place.
Princeton University provides students a subscription to Firsthand, a site featuring in-depth information on what it’s really like to work within an industry, company or profession. Firsthand has list of technical interview questions and an article on why soft skills matter in tech.
There are a vast array of books on the topic of technical interview prep. A few recent books include:
- Cracking the Coding Interview 6th ed. (2020) by Gayle Laakmann McDowell
- Elements of Programming Interviews (indiv. guides for C++, Java, Python…) by Adnan Aziz, Tsung-Hsien Lee, and Amit Prakash
- Cracking the PM Interview: How to Land a Product Manager Job in Technology (2013), by Gayle Laakmann McDowell and Jackie Bavaro