Rupee106 Software Engineer Interview: Rounds, Questions and Preparation

What the job involves

A Software Engineer at an Indian unicorn or high-growth startup builds and ships product features quickly, often across the full stack, in a fast-changing environment. You will write code, debug production issues, review peers' code, and collaborate with product, design, and operations teams. Expect ownership of small services or modules early, with a focus on measurable user or business impact.

Role and Technical Knowledge

1. 1

   Explain the difference between a process and a thread, and why it matters for a backend service handling many requests.

   Cover memory sharing, context switching cost, and how threads or processes affect concurrency and resource use in a service.

2. 2

   How would you design a REST API for a wallet or payments feature that lets users check balance and make a transfer?

   Mention resource naming, HTTP methods, idempotency keys for transfers, status codes, and basic validation.

3. 3

   What is database indexing, and when would adding an index hurt performance?

   Explain how indexes speed reads but slow writes and take space, and give a case like a low-cardinality column or write-heavy table.

4. 4

   Given an array of integers, find two numbers that add up to a target. How would you optimize from brute force?

   Start with O(n^2), then use a hash map for O(n), and discuss edge cases like duplicates and no solution.

Practical Scenarios

1. 5

   A feature you shipped is causing slow response times in production. How do you debug it?

   Describe checking logs and metrics, reproducing the issue, isolating the bottleneck, and rolling back or hotfixing safely.

2. 6

   You need to add a new field to an existing database table used by a live app. How do you do it without downtime?

   Cover backward-compatible migrations, adding nullable columns, backfilling data, and deploying code before enforcing constraints.

3. 7

   Your team wants to move a monolith feature to a microservice. What factors would you consider?

   Discuss team ownership, deployment independence, data consistency, network latency, and whether the split solves a real problem.

4. 8

   How would you handle a bug report from a customer that you cannot reproduce locally?

   Mention gathering details, checking production data and logs, adding instrumentation, and communicating clearly with support.

Problem Solving and Code Quality

1. 9

   Write a function to detect if a linked list has a cycle. Explain your approach and complexity.

   Use Floyd's cycle detection, explain slow and fast pointers, and state O(n) time and O(1) space.

2. 10

   How do you decide between using a SQL and a NoSQL database for a new feature?

   Compare schema flexibility, transactions, consistency needs, query patterns, and scaling approach for the specific use case.

3. 11

   What does clean code mean to you, and how do you ensure it in a fast-paced startup?

   Talk about readable names, small functions, tests, code reviews, and balancing speed with maintainability.

4. 12

   Explain time and space complexity of a solution you wrote recently, and how you would improve it.

   Pick a real example, state the current complexity, and suggest a concrete optimization with trade-offs.

Behavioural and HR

1. 13

   Why do you want to work at a high-growth startup like Rupee106 instead of a large established company?

   Show interest in ownership, speed, learning, and impact, and connect it to your own working style and goals.

2. 14

   Tell me about a time you had to learn a new technology quickly for a project.

   Use STAR format: situation, task, action, result, and highlight how you learned and applied it under time pressure.

3. 15

   Describe a conflict you had in a team project and how you resolved it.

   Focus on listening, data-driven discussion, and a resolution that kept the project moving, not on blaming others.

4. 16

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

   Align your growth with deeper technical ownership, mentoring, and shipping impactful features, not just a title change.