How to Identify Top Developers in Technical Interviews

I once asked an experienced embedded software developer to write a program that reverses a string and prints it to the screen; he struggled, even though he can build robots from spare parts, contributed to satellite projects, and excels in many technical areas, but he had never needed to display output.

Some interviewers know how to ask the right questions to discover great programmers, while others copy generic questions from the internet and lack judgment; a bad hire can cause long‑term damage, and rejecting strong candidates also harms the organization.

A technical interview should consist of three parts: verifying the authenticity of the résumé, assessing the candidate’s real‑world experience, and testing knowledge with Q&A or coding problems.

Part 1: Testing Résumé Authenticity

In one interview a colleague dismissed a candidate for claiming expertise in a technology they had never used; the colleague decided to distrust everything on the résumé unless proven otherwise. I tend to assume résumé claims are unverified until evidence is provided, probing each listed skill with concrete follow‑up questions.

Developed a real‑time operating system as a practice project. How large was your team? What part did you actually handle? Describe what happens when a high‑priority task sends a message to a low‑priority task.

Independently created an audio transmission protocol for a wireless security system. Was it a solo effort? How did you test it? Why didn’t you use RTP?

Fixed bugs in an XXX engine. Describe a particularly challenging bug you discovered and how you resolved it.

Part 2: Discovering Real Experience

Depth of experience is a strong indicator of talent; seasoned developers have learned from mistakes, know when to apply design patterns, and can sense which requirements need changes. Not all experience is equal—some engineers write and refactor code across many projects, while others make minimal changes over years.

Many great programmers start coding in their second year of university or even earlier; such early experience is rarely listed on résumés and must be elicited during the interview.

How did you get into software development?

What was the first programming language you learned?

Experience Density

Personal coding projects outside of work demonstrate richer experience. Additional indicators include working in small teams, participating in many diverse projects, having detailed knowledge of multiple abstraction layers in a large system, and serving as a primary developer on a project.

Worked in a very small team or subgroup.

Participated in many varied projects.

Possess detailed understanding of all abstraction layers of a large system.

Acted as a main developer within a project team.

Part 3: Verifying Experience

After gauging a candidate’s overall experience level, conduct focused questions to verify concrete coding knowledge; a few minutes are insufficient for a thorough test, so multiple interviewers often collaborate to cover different domains.

Common topics include:

Data structures and algorithms

Multithreading

Byte manipulation

Memory allocation

Objects, inheritance, design patterns

Recursion

Assembly language and program execution principles

Each area should have a basic question (e.g., “What is a signal?”) and deeper follow‑up questions to confirm expertise; for instance, asking an embedded developer to convert 0x4C to binary should reveal whether they truly understand the concept.

Coding Problems

After the previous steps, a coding problem serves as the final hurdle; plan the problem carefully based on the candidate’s experience, ensuring relevance to the role.

The problem statement must be precise and unambiguous; vague descriptions lead to misunderstandings and wasted time. After a few minutes of coding, ask the candidate to explain their approach to confirm correct interpretation.

Going Further

These guidelines focus on experience‑based evaluation and may miss high‑potential candidates with limited experience; non‑coding puzzles can assess problem‑solving ability.

Assume the candidate is a strong developer and consider the qualities they should exhibit; while you cannot measure these qualities perfectly, thorough questioning brings you close to an accurate assessment.