Public App Software Engineer Interview: Rounds, Questions and Preparation

What the job involves

Software Engineers at Indian unicorns and high-growth startups build and ship features for consumer-facing products that scale to millions of users. The day-to-day involves writing production code, debugging live issues, collaborating with product and design, and optimising for performance and reliability. Freshers are expected to learn quickly, take ownership of small modules, and contribute to fast release cycles.

Role and Technical Knowledge

1. 1

   How would you design a URL shortener for a fast-growing social media app?

   Cover hashing, database choice, caching, and handling high read traffic. Mention trade-offs between consistency and availability.

2. 2

   Explain the difference between SQL and NoSQL databases. When would you use each in a startup product?

   Discuss schema flexibility, scaling, and use cases like user profiles (SQL) vs. activity feeds (NoSQL). Relate to real product needs.

3. 3

   What happens when you type a URL in a browser and press enter?

   Walk through DNS, TCP, HTTP, server response, and rendering. Show understanding of networking and web fundamentals.

4. 4

   How do you ensure your code is testable and maintainable in a fast-paced startup?

   Mention unit tests, modular design, code reviews, and CI/CD. Emphasise balancing speed with quality.

Practical Scenarios

1. 5

   You are asked to add a new feature to a live app with millions of users. How do you approach it?

   Discuss feature flags, gradual rollout, monitoring, and rollback plans. Show awareness of production risks.

2. 6

   A bug is reported in production that affects 10% of users. How do you debug and fix it?

   Outline steps: reproduce, check logs, isolate, fix, test, deploy. Mention communication with the team.

3. 7

   How would you optimise a slow API endpoint that returns user feed data?

   Suggest caching, pagination, database indexing, and query optimisation. Consider load testing and profiling.

4. 8

   You need to integrate a third-party payment service. What factors do you consider?

   Cover security, error handling, retries, idempotency, and compliance. Show awareness of failure modes.

Behavioural and Teamwork

1. 9

   Tell me about a time you worked in a team to deliver a project under a tight deadline.

   Use STAR method. Highlight your role, collaboration, and how you handled pressure.

2. 10

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

   Show empathy, communication, and focus on data or user impact. Avoid blaming others.

3. 11

   Give an example of a time you learned a new technology quickly to solve a problem.

   Explain the context, your learning approach, and the outcome. Show curiosity and self-drive.

4. 12

   How do you prioritise tasks when you have multiple deadlines?

   Mention impact, urgency, and communication with stakeholders. Use a framework like Eisenhower matrix.

HR and Motivation

1. 13

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

   Show understanding of startup pace, ownership, and learning opportunities. Align with your career goals.

2. 14

   Where do you see yourself in three years?

   Focus on skill growth, taking more responsibility, and contributing to the product. Avoid vague answers.

3. 15

   What do you know about our product and how it impacts users?

   Research the company's app, features, and user base. Mention specific aspects that excite you.

4. 16

   How do you handle feedback and criticism?

   Show openness, willingness to improve, and examples of acting on feedback. Emphasise growth mindset.