Zivame Backend Engineer Interview: Rounds, Questions and Preparation

What the job involves

As a backend engineer at an Indian unicorn or high-growth startup like Zivame, you will design and maintain server-side logic, databases, and APIs that power e-commerce, fintech, or consumer platforms. You will work on scaling systems to handle lakhs of daily transactions, optimising for speed and reliability, and collaborating with frontend, product, and data teams. Expect to write clean, testable code, debug production issues, and continuously improve system performance.

Role and technical knowledge

1. 1

   How would you design a database schema for an e-commerce platform like Zivame that handles products, orders, and users?

   Discuss tables for users, products, orders, order_items, and payments. Mention normalisation, indexing on foreign keys, and handling many-to-many relationships (e.g., product categories).

2. 2

   Explain the difference between SQL and NoSQL databases. When would you choose one over the other for a high-traffic Indian startup?

   Cover ACID vs BASE, scalability, and use cases. For transactional data like orders, SQL is preferred; for unstructured or rapidly changing data like user activity logs, NoSQL may be better.

3. 3

   What is an API gateway and why is it useful in a microservices architecture?

   Explain it as a single entry point for clients, handling authentication, rate limiting, and routing. Mention benefits like decoupling and easier monitoring.

4. 4

   How do you ensure your backend code is secure, especially when handling user data and payments?

   Talk about input validation, parameterised queries to prevent SQL injection, HTTPS, encryption at rest, and following OWASP guidelines. Mention compliance like PCI-DSS if relevant.

Practical scenarios

1. 5

   Your e-commerce site experiences a sudden spike in traffic during a flash sale. How would you prevent the backend from crashing?

   Discuss horizontal scaling, load balancing, caching (Redis), database read replicas, and queueing systems for order processing. Mention auto-scaling in cloud environments.

2. 6

   You notice that a particular API endpoint is slow. How would you debug and optimise it?

   Suggest profiling, checking database queries for missing indexes, adding caching, and optimising code logic. Mention tools like APM or logs.

3. 7

   How would you handle a situation where a third-party payment service is down during checkout?

   Propose fallback mechanisms, retries with exponential backoff, and graceful degradation (e.g., allowing orders with pending payment). Emphasise communication with users.

4. 8

   Describe how you would implement a rate limiter for an API to prevent abuse.

   Explain token bucket or sliding window algorithms, using Redis for distributed rate limiting, and returning 429 status codes. Mention per-user or per-IP limits.

Behavioural and HR

1. 9

   Tell me about a time you worked in a team to build something. What was your role and how did you handle disagreements?

   Use STAR format. Highlight collaboration, listening, and compromise. Show that you value team success over personal ego.

2. 10

   Why do you want to work as a backend engineer at a high-growth startup like Zivame?

   Show passion for solving scale problems, learning quickly, and making an impact. Mention specific aspects of the company's tech or mission that excite you.

3. 11

   Describe a challenging technical problem you faced in a project. How did you overcome it?

   Pick a real example, explain the problem, your approach, and the outcome. Emphasise persistence, research, and asking for help when needed.

4. 12

   Where do you see yourself in three years, and how does this role fit into your career goals?

   Align your growth with the company's needs, such as becoming a strong backend developer or taking on more system design responsibilities. Avoid sounding like you want to leave soon.

Coding and problem-solving

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 use a hash map for O(n) time. Discuss trade-offs and edge cases like duplicates.

2. 14

   How would you detect a cycle in a linked list?

   Explain Floyd's cycle-finding algorithm (tortoise and hare) with O(n) time and O(1) space. Mention alternative using a hash set.

3. 15

   Write a function to check if a string is a valid palindrome, considering only alphanumeric characters and ignoring case.

   Use two pointers from start and end, skipping non-alphanumeric characters. Discuss time O(n) and space O(1).

4. 16

   Design a simple key-value store that supports get, put, and delete operations. How would you handle concurrent access?

   Mention using a hash map with locks (e.g., mutex) or concurrent data structures. Discuss thread safety and potential performance trade-offs.