Key Evaluation Criteria for Software Engineer Interviews

Fundamentals

Engineering skill

• Can the candidate clearly explain the foundations of computer science — algorithms, data structures, and related core concepts?
• Can they clearly explain the purpose and importance of the features they owned on their projects?
• Can they clearly explain how the technologies they used work and how to apply them?
• Do they have the reasoning and problem-solving skills to work through hard problems?
• Can they explain the process they used to solve a hard problem in a way another person can easily follow?

Growth potential

• Can they clearly explain their outcomes on past projects and how they got there?
• Can they clearly explain their strengths and weaknesses as a collaborator?
• Do they have meaningful experience solving problems on their own initiative when things went wrong on a project?
• Do they understand the nature and daily work of the role they’re applying for?
• Did they prepare for the interview — self-introduction, likely questions, etc.?

Work attitude

• Do they have a concrete plan and direction for becoming a better developer?
• Do they have the habits required to keep growing — studying, writing things down, and so on?
• Do they have the persistence to push through hard problems?
• Do they have the fundamentals and habits to learn new technology quickly?

Technical topics

Language

• Explain stack and queue. Explain other data structures.
• Password hashing algorithms.
• Difference between a class and an instance.
• What is TDD? Unit test vs integration test.
• What is OOP? Four main characteristics / core concepts.
• Functional programming.
• What is an abstract class?
• What is an interface?
• Overloading vs overriding — difference and explanation.
• Compilation vs interpretation — difference and explanation.
• What is a buffer?
• Explain design patterns, and the singleton pattern.

OS

• Process vs thread — difference and explanation.
• Data types on a 32-bit CPU, including how many bytes an int is and why.
• Methods of inter-process and inter-thread communication.
• Synchronization problems.
• What is deadlock, and how do you resolve it?
• Race condition, need for synchronization, and critical section.
• What is starvation?
• What is stack overflow?
• What is heap overflow?

Network

• What is HTTP?
• HTTP verbs, their uses, and idempotency.
• PUT vs PATCH.
• Response codes, their uses, and differences.
• HTTP vs HTTPS.
• SSL/TLS handshake.
• Differences across HTTP versions.
• HTTP headers.
• What is a WebSocket?
• TCP vs UDP, and how reliability is guaranteed.
• 3-Way and 4-Way Handshake.
• What is caching?
• URL vs URI.
• What is a proxy?

HTML, CSS

• Difference between div and span.
• What is flexbox layout? Difference vs table, position, etc.
• 100vh vs 100%.
• async vs defer when including a script in HTML.
• px, em, rem differences as size units.
• vw vs vh.
• Browsers’ default font size (16px).
• rem units — what happens if you set 8em?
• What does px really mean? Problems with using px, and when to use it for sizing.
• Semantic markup.
• HTML document structure.
• What is the DOM, and how do you traverse it?
• CSS selector specificity.
• What is flexbox?

Javascript

• Sync vs async, blocking vs non-blocking.
• Data types.
• undefined vs null.
• What is a Promise — then, catch, finally.
• What is an IIFE (Immediately Invoked Function Expression)?
• Explain closures and where they’re used.
• Benefits of const, and thread safety.
• var, let, const — differences and var hoisting.
• ES5 vs ES6.
• Chaining.
• localStorage vs sessionStorage.
• Event bubbling vs capturing.
• One-way vs two-way binding.
• What is this?
• call, apply, bind.
• What is a callback function, why use it, and how to escape callback hell.
• How to convert an async function into sync behavior.
• What is AJAX?
• Explain map, forEach, and reduce.
• What are the call stack and heap?
• What is JWT? What is a refresh token?
• Threads in JavaScript.
• Event loop and task queue.
• Prototype and prototype chain.
• == vs ===.
• Arrow functions.

Typescript

• Overall overview and how it differs from JavaScript.
• Generics.
• Access modifiers — public, private, protected — and usage.
• What is static?

Java

• Overloading vs overriding.
• Interface vs abstract class.
• static.
• Access modifiers — private, public.
• Getters and setters.
• Dependency inversion principle.
• map vs set in data structures.
• Hashtable vs HashMap.
• Spring Boot vs Spring.
• Is Java sync or async? Blocking or non-blocking? How do you use Future to write async code?
• The final keyword.
• equals and hashCode usage.
• Reference types vs primitive types.
• What is dependency injection?
• What is IoC (Inversion of Control)?

Database

• What is an index? Why does an index make search fast?
• Clustered vs non-clustered indexes.
• Binary search.
• Can you explain common sorting approaches?
• Inner join vs outer join.
• Primary key, foreign key, compound key.
• What is a transaction, and why do you need transaction processing?
• RDB vs NoSQL.
• Difference between a view and a table, and when to use each.

Maintenance

• What is Redis used for as a cache server?
• What should you watch out for with Redis — single-threaded nature?
• Message queue (MSMQ).
• How do you ensure sequential processing when a high volume of jobs comes in?
• How do you handle logging?
• For heavy traffic across multiple servers, what software or hardware would you use?

Version Control

• Why use Git?
• commit, push, merge, rebase — differences.
• Why do conflicts happen, and how do you resolve them?
• Do you use Git Flow? Describe a branching workflow you’ve used.

Know-how, misc

• Microservice architecture — have you built one?
• How would you migrate an existing monolith to microservices?
• When you type estgames.com into a browser, walk through what happens to render the page.
• How would you handle a page under heavy load?

Algorithms

• Fastest way to shuffle numbers from 1 to 10,000.
• An algorithm to check whether many running services are healthy.
• Call by value vs call by reference.
• BFS vs DFS — explanation and difference.
• Dynamic programming.
• How does git merge work — or how would you implement merging?
• Time complexity of quicksort.

React

• React pros and cons — why use it?
• React component lifecycle.
• Flux pattern, and how MVVM differs from Flux.
• useEffect vs useLayoutEffect.
• What is the Virtual DOM?
• Callbacks vs Promises.
• Why className instead of class.
• useMemo vs useCallback.
• What is Next.js?
• React Hooks.
• useMemo vs useCallback (again).
• What is memoization?
• React.memo vs useMemo.
• Why use the key prop.
• Prop drilling and how to solve it.
• What is React.FC?
• What is a pure component?
• Class components vs functional components.
• How does setState actually work?
• What is React Query?
• useEffect vs useLayoutEffect (again).
• Redux — pros, cons, and the useReducer hook.
• Context API vs Redux.
• What is Recoil?
• Next.js getStaticProps.

HTML markup

• What is { box-sizing: border-box; } — pros and cons?
• inline vs inline-block.
• relative, fixed, absolute, static — differences.
• What CSS framework have you used locally or in production, and what would you improve?
• Have you used modern CSS Flexbox or Grid specs? Explain.
• Responsive vs adaptive design.
• Have you done retina graphics? If so, when and using what techniques?
• What is srcset?
• What is SVG?
• Why use translate() instead of absolute positioning — and vice versa?
• IE11 compatibility techniques.

Back-end

• HTTP response codes 200, 404, etc.
• Apache vs Tomcat.
• Cookies vs sessions.
• JWT — cookie vs session vs JWT as authentication; refresh token.
• Authentication vs authorization.
• Best practices for authentication and password management.
• Managing code that must not run concurrently.
• What is a preflight request?
• What is OAuth?
• Token-based authentication — Basic, Bearer.

Front-end

• From a network perspective, what happens in order when you access a website?
• Explain the browser’s rendering pipeline.
• How does a browser work?
• Webpack, Babel, polyfills.
• CSR vs SSR.
• SEO basics.
• CORS — explanation.
• Cookies vs sessions (front-end angle).
• XSS attacks.
• Local Storage vs Session Storage vs cookies.
• Token-based authentication.
• Cross-browser compatibility.
• WebSockets.
• Website performance optimization.
• How to measure website performance.
• How to reduce bundle size.
• What is code splitting?
• HTTP (HyperText Transfer Protocol).
• What are web standards?
• Reflow and repaint.
• What is Storybook?
• Buffering — when does it happen?
• V8 engine — inline caching, TurboFan.
• MVC vs MVVM.
• Web server vs WAS (web application server).
• What is NestJS, and what makes it distinct?
• Promise vs callback.
• GraphQL vs REST API.
• What is a UUID?