Interview questions by language
The conceptual questions interviewers actually ask about a language — closures and the event loop in JavaScript, decorators and the GIL in Python — each with a model answer. Every language also has a scored AI practice room.
Every language page collects the conceptual questions interviewers return to most often, grouped into a basic and an advanced track, each with a model answer you can say out loud. The goal is not to memorise a list but to rehearse explaining a concept clearly while under a little pressure.
Start with the basic track for the language on the job description, then move to advanced. When an answer still feels shaky out loud, open the scored Fundamentals room and answer the same question for feedback — the gap between "I know it" and "I can say it" is where interviews are won and lost.
40 questions — 20 basic and 20 advanced. Example: What is the difference between var, let, and const?
40 questions — 20 basic and 20 advanced. Example: When would you use a list, tuple, set, or dict?
40 questions — 20 basic and 20 advanced. Example: What's the difference between the JDK, JRE, and JVM?
40 questions — 20 basic and 20 advanced. Example: What's the difference between a pointer and a reference?
40 questions — 20 basic and 20 advanced. Example: What is the difference between value types and reference types?
40 questions — 20 basic and 20 advanced. Example: What's the difference between an array and a slice?
How to use this question bank
- Pick the language that appears in the job description and read the basic questions first.
- Answer each question out loud before you read the model answer and its key points.
- Move to the advanced track and re-practise the questions you cannot explain in three sentences.
- Open the scored Fundamentals room and answer the same questions for a communication score.
Common questions
Are these interview questions free?
Yes. The full question bank for every language — JavaScript, Python, Java, C++, C#, and Go — is free to read, and every question comes with model answers and key points.
How are basic and advanced questions different?
Basic questions cover the mechanics everyone is expected to know, such as value vs reference semantics or the event loop. Advanced questions push into tradeoffs, internals, and edge cases like memory models, concurrency, and undefined behaviour.
Should I memorise the model answers?
No. Use them as a structure, not a script. Read the answer, close the page, and explain the concept in your own words out loud, then practise the same question in the Fundamentals room for a score.
How many questions should I prepare before an interview?
A handful per language, deeply understood, beats a long list skimmed once. Start with the advanced questions for the language in the job description and rehearse them until the explanation is automatic.
Keep preparing
How to rehearse coding and system design — run the technical rounds against an AI interviewer.
Behavioral interview questions and how to answer them — the other half of the loop.
Want feedback on your answers? Start free and rehearse with a scored AI interviewer.