Hirect Full Stack Developer Interview: Rounds, Questions and Preparation

What the job involves

A Full Stack Developer at Indian unicorns and high-growth startups like Hirect builds and maintains both client-side and server-side components of web applications, often working across the entire stack from UI to database. Day to day, you might write React components, design REST APIs, optimise database queries, and deploy features rapidly in an agile environment. Expect close collaboration with product, design, and other engineers to ship user-facing features that scale to millions of users.

Role and Technical Knowledge

1. 1

   What is the difference between REST and GraphQL, and when would you choose one over the other in a startup environment?

   Explain that REST uses fixed endpoints while GraphQL allows clients to request specific data. For startups, GraphQL can reduce over-fetching but REST is simpler and faster to implement for basic CRUD.

2. 2

   How does the event loop work in Node.js, and why is it important for handling multiple requests in a high-traffic app?

   Cover the single-threaded event loop, non-blocking I/O, and how it enables concurrency. Mention that blocking operations can degrade performance, so offload heavy tasks.

3. 3

   Explain the concept of state management in React. How would you manage global state in a large application?

   Discuss local vs global state, and tools like Context API, Redux, or Zustand. Emphasise choosing based on app complexity and avoiding over-engineering.

4. 4

   What are some key considerations when designing a database schema for a social feed or job listing platform?

   Mention indexing, denormalisation for read performance, handling relationships (e.g., users, posts, applications), and choosing between SQL and NoSQL based on access patterns.

Practical Scenarios

1. 5

   You are building a feature to allow users to apply for jobs with a single click. How would you design the frontend and backend to ensure it is fast and reliable?

   Outline optimistic UI updates on frontend, an API endpoint that handles application creation, and idempotency to prevent duplicate applications. Mention error handling and feedback to user.

2. 6

   Your app is experiencing slow API response times during peak hours. How would you diagnose and fix the issue?

   Talk about monitoring tools, checking database queries, adding caching (Redis), and scaling horizontally. Suggest profiling to find bottlenecks.

3. 7

   You need to implement authentication and authorization for a new dashboard. What approach would you take?

   Explain JWT or session-based auth, role-based access control, and secure storage of tokens. Mention OAuth for social login if needed.

4. 8

   How would you handle file uploads (e.g., resumes) in a MERN stack application?

   Describe using multer on backend, storing files in cloud storage (S3), and saving metadata in database. Discuss validation and size limits.

Behavioural and HR

1. 9

   Tell me about a time you had to learn a new technology quickly for a project. How did you approach it?

   Use STAR method: describe the situation, the technology, your learning strategy (docs, tutorials, small prototypes), and the outcome. Highlight adaptability.

2. 10

   Describe a situation where you disagreed with a teammate on a technical approach. How did you resolve it?

   Show that you listen, provide data or reasoning, and aim for consensus. Emphasise teamwork over being right.

3. 11

   Why do you want to work at a fast-growing startup like Hirect instead of a larger, more established company?

   Express enthusiasm for wearing multiple hats, learning rapidly, and having direct impact. Connect your skills to the company's mission and product.

4. 12

   How do you prioritise tasks when you have multiple deadlines? Give an example.

   Discuss using urgency and impact, communicating with stakeholders, and using tools like Trello or Jira. Provide a concrete example from college projects or internships.

Problem Solving and Coding

1. 13

   Given an array of integers, find two numbers that add up to a specific target. How would you optimise the solution?

   Start with brute force O(n^2), then explain using a hash map for O(n) time. Mention edge cases like duplicates or no solution.

2. 14

   Write a function to check if a binary tree is a valid binary search tree.

   Explain in-order traversal or recursive min/max bounds. Discuss time and space complexity.

3. 15

   How would you find the first non-repeating character in a string?

   Use a hash map to count frequencies, then iterate to find first with count 1. Consider Unicode characters and empty string.

4. 16

   Implement a debounce function in JavaScript. Where would you use it in a full-stack app?

   Explain that debounce limits function calls, useful for search input or window resize. Provide a simple implementation with setTimeout and clearTimeout.