InMobi Software Engineer Interview: Rounds, Questions and Preparation

What the job involves

Software Engineers at Indian unicorns and high-growth startups like InMobi build and scale consumer-facing products, often working on mobile-first systems, large-scale data pipelines, and cloud infrastructure. Day to day, you write production code, debug live issues, participate in code reviews, and collaborate with product and design teams to ship features fast. Expect a mix of feature development, performance tuning, and on-call responsibilities in a fast-paced, metrics-driven environment.

Role and Technical Knowledge

1. 1

   How would you design a URL shortener that can handle millions of requests per day for a mobile ad-tech company?

   Cover hashing, database choice (NoSQL for scale), caching, and load balancing. Mention trade-offs between consistency and availability.

2. 2

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

   Discuss schema flexibility, scaling (horizontal vs vertical), and use cases like user profiles vs real-time analytics. Relate to mobile ad data.

3. 3

   What happens when you type a URL into a browser and press Enter? Walk me through the entire process.

   Cover DNS resolution, TCP handshake, HTTP request, server response, and rendering. Highlight caching and CDN for fast mobile experiences.

4. 4

   How do you find the middle of a linked list in one pass? Write the code and explain its time complexity.

   Use the two-pointer (slow and fast) technique. Explain O(n) time and O(1) space, and mention edge cases like even-length lists.

Practical Scenarios

1. 5

   Your production API is suddenly returning 500 errors for 10% of users. How do you debug and resolve this?

   Check logs, monitor dashboards, reproduce locally, and roll back if needed. Emphasise communication with the team and post-mortem learning.

2. 6

   You need to reduce the load time of a mobile app's home screen by 50%. What steps would you take?

   Mention profiling, image compression, lazy loading, caching, and reducing API calls. Prioritise based on user impact and effort.

3. 7

   How would you handle a situation where your code works locally but fails in the staging environment?

   Compare environments (dependencies, config, data), check CI/CD logs, and use debugging tools. Highlight systematic isolation of variables.

4. 8

   You are asked to add a new feature that conflicts with an existing one. How do you proceed?

   Discuss with product and tech leads, assess impact, propose alternatives, and document decisions. Show collaboration and user-centric thinking.

Behavioural and HR

1. 9

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

   Show passion for impact, ownership, and fast-paced learning. Mention specific startup traits like agility and innovation.

2. 10

   Tell me about a time you worked in a team to solve a difficult problem. What was your role?

   Use STAR method. Highlight your contribution, how you handled disagreements, and the outcome. Emphasise teamwork and communication.

3. 11

   Describe a situation where you had to learn a new technology quickly for a project. How did you manage?

   Show self-learning ability, resourcefulness, and time management. Give a concrete example with a positive result.

4. 12

   Where do you see yourself in three years, and how does this role fit into that plan?

   Align your growth with the company's needs. Mention gaining deep technical expertise and taking on more ownership.

Problem Solving and Coding Approach

1. 13

   Given an array of integers, find two numbers that add up to a target sum. How would you optimise from O(n^2) to O(n)?

   Use a hash map to store complements. Explain the trade-off between time and space, and handle duplicates.

2. 14

   How would you detect a cycle in a linked list? Explain the algorithm and its complexity.

   Use Floyd's cycle-finding algorithm (tortoise and hare). Explain O(n) time and O(1) space, and how to find the start of the cycle.

3. 15

   Write a function to reverse a string in place. What are the edge cases you need to consider?

   Use two pointers swapping from ends. Mention empty strings, Unicode, and memory constraints. Show clean code with comments.

4. 16

   You have a list of user IDs and their scores. How would you find the top 10 scores efficiently?

   Use a min-heap of size 10 for O(n log k) time. Discuss trade-offs with sorting and when to use each approach.