Bombay Shaving Company Full Stack Developer Interview: Rounds, Questions and Preparation

What the job involves

As a Full Stack Developer at an Indian unicorn or high-growth startup, you will build and maintain both client-side and server-side components of web applications, often working across the entire stack from database to UI. You will collaborate with product managers, designers, and other engineers to ship features quickly, iterate based on user feedback, and ensure scalability and performance in a fast-paced environment. Expect to handle multiple responsibilities, from writing clean code to deploying and monitoring applications.

Role and Technical Knowledge

1. 1

   Explain the difference between REST and GraphQL APIs. When would you choose one over the other in a startup environment?

   A strong answer contrasts REST's multiple endpoints with GraphQL's single endpoint and flexible queries, and discusses trade-offs like over-fetching, caching, and development speed. Mention startup needs for rapid iteration and client-specific data fetching.

2. 2

   How do you ensure the security of a full stack application, from frontend to database?

   Cover input validation, authentication (JWT, OAuth), authorization, HTTPS, secure cookies, SQL injection prevention, and environment variable management. Highlight awareness of OWASP top 10 and practical measures like rate limiting.

3. 3

   What is the event loop in Node.js and how does it affect performance?

   Explain the event loop's role in non-blocking I/O, phases like timers, poll, and check, and how it enables concurrency. Discuss potential blocking operations and how to avoid them with async patterns.

4. 4

   Describe how you would optimize a slow-performing React application.

   Mention profiling with React DevTools, code splitting, lazy loading, memoization (React.memo, useMemo), virtualized lists, and reducing re-renders. Also consider bundle size analysis and image optimization.

Practical Scenarios

1. 5

   You are building a feature for a high-traffic e-commerce site during a flash sale. How would you design the system to handle sudden spikes in traffic?

   Discuss load balancing, horizontal scaling, caching (Redis), database read replicas, queueing for writes, and CDN for static assets. Mention monitoring and auto-scaling groups.

2. 6

   A bug is reported in production where users cannot complete checkout. How do you debug and resolve it?

   Outline steps: reproduce, check logs and error tracking (Sentry), inspect recent deployments, use debugging tools, and communicate with the team. Emphasize quick rollback if needed and post-mortem.

3. 7

   You need to integrate a third-party payment gateway into the application. What factors do you consider?

   Cover API documentation, sandbox testing, security (PCI compliance), error handling, webhooks, idempotency, and user experience during failures. Mention handling edge cases like network timeouts.

4. 8

   How would you approach migrating a monolithic application to microservices?

   Discuss identifying bounded contexts, incremental migration, API gateway, inter-service communication, data consistency, and deployment strategies. Highlight trade-offs and avoiding over-engineering.

Behavioral and HR

1. 9

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

   Use STAR method: describe the situation, the technology, your learning approach (docs, tutorials, small prototypes), and the outcome. Show adaptability and self-driven learning.

2. 10

   Describe a situation where you disagreed with a team member on a technical approach. How did you handle it?

   Focus on respectful communication, data-driven discussion, and willingness to compromise. Highlight the importance of team goals over personal preferences.

3. 11

   Why do you want to work at a high-growth startup like ours instead of a large MNC?

   Express enthusiasm for fast-paced environments, ownership, and impact. Connect personal goals with startup culture, and mention specific aspects of the company's product or mission.

4. 12

   How do you prioritize tasks when you have multiple deadlines?

   Discuss using frameworks like Eisenhower matrix, communicating with stakeholders, and focusing on high-impact tasks. Give an example of a time you managed competing priorities successfully.

Coding and Problem Solving

1. 13

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

   Start with brute force O(n^2), then explain using a hash map for O(n) time. Discuss edge cases and space-time trade-offs.

2. 14

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

   Explain recursive approach with min/max bounds or in-order traversal. Discuss time complexity O(n) and space O(h). Mention handling duplicates if allowed.

3. 15

   How would you implement a debounce function in JavaScript?

   Describe using setTimeout and clearTimeout, with a closure to preserve timer. Show code and explain use cases like search input to reduce API calls.

4. 16

   Design a database schema for a simple e-commerce application with users, products, orders, and order items.

   Outline tables with primary keys, foreign keys, and relationships. Discuss normalization, indexes for performance, and considerations for scalability.