Q1
Walk me through how you would design a REST API endpoint that handles concurrent requests and returns paginated results. What considerations would you make for performance and scalability?
Why they ask this:* They're assessing your ability to design practical APIs, understand concurrency issues, and think about real-world constraints like performance and database load—essential skills for mid-level engineers.
Q2
Explain a time when you had to debug a memory leak or performance bottleneck in production. What tools did you use, and how did you identify the root cause?
Why they ask this:* They want to evaluate your hands-on experience with production issues, your debugging methodology, and whether you can use profiling tools effectively—critical for maintaining system reliability.
Q3
Describe your approach to writing unit tests and integration tests. What's the difference, and how do you decide what to test?
Why they ask this:* This reveals your understanding of testing strategy, code quality practices, and whether you think about maintainability—traits of engineers who ship reliable code consistently.
Q4
How would you approach refactoring a monolithic codebase into microservices? What are the trade-offs you'd consider?