Interview Prep: Common Developer Interview Questions & Answers (2026 Guide)

Preparing for a developer interview can feel overwhelming — there is so much ground to cover, the technology landscape shifts constantly, and you never quite know which questions are going to come up. But here is the truth most candidates miss: interviews follow patterns. The questions change, the tech stack changes, but the underlying areas being tested stay remarkably consistent.

Whether you are a fresher stepping into your first technical round or an experienced developer targeting a senior role, this guide covers the most commonly asked questions across all categories — general, technical, framework-specific, JavaScript, database, system design, and behavioural — with honest answers and the thinking behind each one.

General Developer Interview Questions

1. What programming languages are you most comfortable with?

This is almost always the first question and most candidates answer it too broadly. The interviewer is not just asking what you know — they are testing whether you have genuine depth or just surface familiarity.

Strong answer approach: Name your primary language, give a specific framework or area you have worked in, and briefly mention a real project or outcome. Keep it under 60 seconds.

Example answer: "I primarily work with PHP and JavaScript. On the backend I have strong experience with Laravel — including building REST APIs, working with Eloquent ORM, and setting up queue workers for background jobs. On the frontend I work with Vue.js and have built several SPAs with Inertia.js. I also have solid MySQL experience including query optimisation and indexing." Check out our guide on Laravel 12 features you should know to brush up before your interview.

2. What is the difference between frontend and backend development?

A deceptively simple question that reveals whether you understand the full picture of web development or just your own corner of it.

• Frontend — everything the user sees and interacts with. HTML, CSS, JavaScript, browser rendering, performance, accessibility, responsive design, and UI state management. Runs in the browser.
• Backend — everything the user never sees. Business logic, databases, authentication, APIs, server configuration, file storage, background jobs, and security. Runs on a server.
• Full stack — a developer comfortable working across both. In practice, most full-stack developers have a stronger side — own yours and be honest about it.

3. How do you keep your technical skills up to date?

Interviewers ask this to gauge whether you are self-directed or passive in your learning. Generic answers like "I read blogs" land flat.

Strong answer: Mention specific sources — official documentation, specific YouTube channels, GitHub repos you follow, open source contributions, or side projects where you deliberately try new tools. Concrete beats vague every time.

Core Programming and Technical Questions

4. What is a REST API?

REST (Representational State Transfer) is an architectural style for building scalable, stateless web services over HTTP. A REST API exposes resources (users, products, orders) via URLs and lets clients interact with them using standard HTTP methods:

GET    /api/users          → retrieve all users
GET    /api/users/1        → retrieve user with ID 1
POST   /api/users          → create a new user
PUT    /api/users/1        → update user with ID 1 (full update)
PATCH  /api/users/1        → partial update of user with ID 1
DELETE /api/users/1        → delete user with ID 1

Key properties of REST: stateless (server stores no session between requests), uniform interface (consistent URL patterns), and cacheable (GET responses can be cached). Read our post on the brand new HTTP QUERY method (RFC 10008) to understand the latest evolution of HTTP methods.

5. What is MVC architecture?

MVC (Model-View-Controller) is a design pattern that separates an application into three distinct layers, each with a specific responsibility:

• Model — handles data, business rules, and database interactions. In Laravel, this is your Eloquent models and service classes.
• View — responsible for presenting data to the user. In Laravel + Vue, your Vue components are the view layer.
• Controller — receives user requests, interacts with the model to get data, and passes that data to the view. Acts as the coordinator between Model and View.

The benefit of MVC is separation of concerns — each layer has one job, making code easier to test, maintain, and scale. If you are asked to draw or explain the request lifecycle in MVC, walk through what happens from the moment a user submits a form to the moment they see the result.

6. What is the difference between SQL and NoSQL databases?

// SQL (MySQL, PostgreSQL)
- Structured tables with fixed schemas
- ACID compliance (Atomicity, Consistency, Isolation, Durability)
- Strong relationships via foreign keys and JOINs
- Best for: transactional systems, financial apps, structured data

// NoSQL (MongoDB, Redis, Cassandra)
- Schema-less, flexible document/key-value/graph structure
- Horizontal scaling built-in
- Eventually consistent (in most cases)
- Best for: large-scale unstructured data, caching, real-time apps

Do not just list the differences — know when to use which. SQL when data integrity and relationships matter. NoSQL when scale, speed, and flexibility matter more than strict consistency. Our guide on database normalisation covers SQL database design fundamentals worth reviewing.

7. What is OOP and what are its four pillars?

Object-Oriented Programming organises code around objects — self-contained units that combine data (properties) and behaviour (methods). The four pillars:

• Encapsulation — hiding internal details and exposing only what is necessary through public interfaces. Private properties and getter/setter methods.
• Abstraction — exposing only relevant details and hiding implementation complexity. Interfaces and abstract classes in Java.
• Inheritance — a class can inherit properties and methods from a parent class, promoting code reuse.
• Polymorphism — the same method name can behave differently depending on the object calling it. Method overriding and overloading.

For PHP and Java OOP concepts in depth, check our guide on PHP OOP programming design patterns .

Framework and Web Development Questions

8. Why use a framework like Laravel?

This question is testing your understanding of trade-offs, not your loyalty to a tool. The honest answer covers what frameworks give you and what they cost:

What you gain: Built-in solutions for routing, authentication, validation, database abstraction (ORM), queuing, caching, file storage, testing utilities, and security features (CSRF protection, SQL injection prevention). You move faster on solved problems and focus effort on your actual business logic.

What you give up: Some performance overhead compared to raw PHP, a learning curve, and occasional constraints when the framework's conventions do not match your use case.

Strong answer addition: Mention a specific Laravel feature you have used that saved significant development time — queues, Sanctum for API auth, or Laravel Scout for search.

9. What is middleware?

Middleware sits between the HTTP request coming in and the controller that handles it. It can inspect, modify, redirect, or reject a request before it reaches your business logic.

// Common middleware use cases
→ Authentication check (is the user logged in?)
→ Authorization (does this user have permission?)
→ CORS headers (is this origin allowed?)
→ Rate limiting (has this IP exceeded the request limit?)
→ Request logging (record what was requested and when)
→ Input sanitization (clean up incoming data)

In Laravel, middleware is registered in Kernel.php and can be applied globally, to route groups, or to individual routes.

10. What is CORS and why does it exist?

CORS (Cross-Origin Resource Sharing) is a browser security feature that blocks frontend JavaScript from making requests to a different domain than the one that served the page — unless the server explicitly allows it.

For example, if your Vue app is running on app.example.com and your API is on api.example.com, the browser blocks the request by default. The API server must respond with the appropriate Access-Control-Allow-Origin header to permit it.

CORS errors are one of the most common issues developers hit when building SPAs with separate frontend and backend. Knowing this deeply — preflight requests, allowed headers, credentials — separates a junior developer from a mid-level one.

JavaScript and Frontend Questions

11. What is the difference between var, let, and const?

// var — function scoped, hoisted, can be re-declared
var x = 1;
if (true) {
  var x = 2; // same variable — overwrites the outer x
}
console.log(x); // 2 — surprising for most beginners

// let — block scoped, not hoisted, cannot be re-declared
let y = 1;
if (true) {
  let y = 2; // different variable — only exists inside this block
}
console.log(y); // 1

// const — block scoped, must be initialised, cannot be reassigned
const z = 1;
z = 2; // TypeError: Assignment to constant variable

// Note: const does NOT make objects immutable
const obj = { name: "Randhir" };
obj.name = "Priya"; // this works — the reference is const, not the content

Rule of thumb: Use const by default. Use let when you need to reassign. Never use var in modern code. For more JavaScript fundamentals, see our guide on JavaScript tips and tricks every developer should know .

12. What is the difference between == and === in JavaScript?

// == performs type coercion before comparing
"5" == 5    // true  — string converted to number
null == undefined // true
[] == 0     // true  — surprising!

// === compares value AND type — no conversion
"5" === 5   // false
null === undefined // false

Always use === in production code. Type coercion in == causes subtle bugs that are extremely hard to debug.

13. What are Promises and async/await?

JavaScript is single-threaded. Promises and async/await let you handle asynchronous operations (API calls, file reads, timers) without blocking the main thread. We have a full dedicated guide on this topic:

👉 Read our complete guide: JavaScript Promises vs Async/Await — Which One Should You Use?

14. What is state management?

State management refers to how your application stores and shares data between components. When two components that are not parent-child need to share data, passing props up and down becomes messy — that is when you need a state management solution.

• Vue: Pinia (recommended in Vue 3), Vuex (Vue 2)
• React: Redux Toolkit, Zustand, Context API
• Angular: NgRx, services with RxJS

Data Structures and Algorithms Questions

15. What is the time complexity of common array operations?

Access by index:      O(1)    — direct memory calculation
Search (unsorted):    O(n)    — must check every element
Search (sorted):      O(log n) — binary search
Insert at end:        O(1)    — amortized
Insert at beginning:  O(n)    — all elements shift
Delete at end:        O(1)
Delete at beginning:  O(n)    — all elements shift
Sort:                 O(n log n) — comparison-based lower bound

16. What is the Two Sum problem and how do you solve it optimally?

// Given an array and a target, find two numbers that sum to target
// Optimal: O(n) time using a HashMap

function twoSum(nums, target) {
  const map = new Map();
  for (let i = 0; i < nums.length; i++) {
    const complement = target - nums[i];
    if (map.has(complement)) {
      return [map.get(complement), i];
    }
    map.set(nums[i], i);
  }
}

twoSum([2, 7, 11, 15], 9); // [0, 1]

Arrays are the most commonly tested data structure in coding interviews. For a comprehensive guide covering 8 of the most asked array problems with full solutions in JavaScript and Java, see our dedicated post:

👉 Array Coding Interview Problems — Two Sum, Kadane's Algorithm, Sliding Window and More

Exception Handling and Error Management

17. How do you handle errors in your code?

This is a frequently asked question that reveals your maturity as a developer. A strong answer covers multiple levels:

• Input validation — validate before processing, not after something breaks.
• Try-catch blocks — for recoverable exceptions, especially around external calls (APIs, file reads, database operations).
• Logging — log errors with context, not just the message. What was the input? What was the state? What user triggered it?
• Graceful degradation — show the user a meaningful message, not a raw stack trace or a blank screen.

For Java specifically, our full guide on exception handling in Java covers checked vs unchecked exceptions, custom exceptions, and best practices in depth.

Behavioural and HR Questions

18. Tell me about a challenging project you worked on

Use the STAR framework — Situation, Task, Action, Result. Do not just describe the project — describe the specific challenge, the decision you made, and the measurable outcome.

Weak answer: "I worked on an e-commerce site and it was complicated because there were many features."

Strong answer: "The payment gateway integration kept failing for specific card types on mobile. I isolated the issue to an encoding problem in the request headers by adding detailed logging to every step of the payment flow. Once identified, I fixed it in 2 hours and the mobile conversion rate improved by 18% the following week."

19. How do you handle tight deadlines?

Interviewers are testing whether you panic or prioritise. The answer they want to hear has three parts: breaking the work into deliverable chunks, communicating early when scope is at risk, and being willing to ship a working smaller version rather than a broken complete version.

Never say "I just work longer hours." That signals poor estimation and unsustainable work habits. Say "I identify which features are truly required for launch versus which are nice-to-have, communicate the trade-off to the team, and deliver the core requirements on time."

20. Where do you see yourself in 5 years?

This question is about ambition and self-awareness. You do not need a perfect plan — you need to show you are thinking about growth. Mention a direction: deeper technical expertise, moving into architecture, leading a team, building your own product. Show that you have thought about it without locking yourself into something implausible.

Questions You Should Ask the Interviewer

Always have 3–4 questions ready. Asking nothing signals disinterest. Asking the right questions signals maturity:

• "What does the onboarding process look like for new developers?"
• "What is the tech stack and how does the team make decisions about adopting new tools?"
• "How does the team handle technical debt?"
• "What does success look like in this role after 90 days?"
• "What is the deployment process — how often do you ship to production?"

Tips to Crack Developer Interviews

• Revise fundamentals before frameworks — interviewers at good companies care more about how you think than which tool you know.
• Practice coding problems daily — even 30 minutes a day for 4–6 weeks before an interview makes a measurable difference. Focus on arrays, strings, hashmaps, and recursion first.
• Build real-world projects — a GitHub profile with two or three genuinely finished projects beats a resume full of technologies with no evidence of use.
• Think aloud during coding rounds — silence during a live coding interview reads as stuck. Narrate your thinking even when you are not sure. Interviewers want to see your process.
• Know your resume cold — every line on your resume is fair game. If you mention a project, know the tech choices you made, the challenges you faced, and the outcome.
• Ask clarifying questions on coding problems — jumping to code without clarifying the problem is a common mistake. Ask about edge cases, constraints, and expected complexity before writing a line.

Related Guides to Help You Prepare

Final Thought

Developer interviews test technical knowledge, but they also test how you think, how you communicate, and how you handle uncertainty. The candidates who stand out are not always the ones who know the most — they are the ones who approach unknown problems methodically, ask smart questions, explain their reasoning clearly, and show genuine curiosity about the work.

Consistency beats cramming. Review one or two topics every day for six weeks before an interview and you will feel genuinely prepared — not just rehearsed.

Have a specific interview question you are struggling to answer? Drop us a message on our contact page — we will help you work through it.