Postman Software Engineer Interview: Rounds, Questions and Preparation

What the job involves

A software engineer at an Indian SaaS or B2B product company builds and maintains features for web-scale products used by other businesses, often working on APIs, dashboards, integrations, and developer-facing tools. The day-to-day involves writing code, reviewing pull requests, debugging production issues, and collaborating with product, design, and support teams. Freshers typically start with well-scoped tasks and grow into owning modules or services.

Role and technical knowledge

1. 1

   What happens when a user sends a request to a REST API in a SaaS product?

   Cover the client sending an HTTP request, server routing, authentication, business logic, database access, and returning a JSON response with status codes.

2. 2

   How would you design a simple API endpoint for a B2B product that returns a list of workspaces for a user?

   Mention authentication, authorization checks, pagination, filtering, database query, and a clear JSON response structure.

3. 3

   Explain the difference between SQL and NoSQL databases and when you would choose one for a SaaS feature.

   Discuss schema flexibility, transactions, scaling, and give a concrete example like user accounts in SQL vs logs in NoSQL.

4. 4

   What is the role of caching in a high-traffic B2B product?

   Explain reducing database load, improving latency, cache invalidation, and where to place caches like Redis or CDN.

Practical scenarios

1. 5

   A customer reports that their API calls are failing intermittently. How would you debug this?

   Check logs, reproduce the issue, look at rate limits, network errors, authentication tokens, and recent deployments.

2. 6

   You need to add a new feature to an existing codebase you have never seen. What steps do you take?

   Read documentation, run the code locally, trace the relevant modules, write a small test, and make a minimal change.

3. 7

   How would you handle a situation where your code passes tests locally but fails in production?

   Compare environments, check configuration, dependencies, data differences, and use production logs and monitoring.

4. 8

   You are asked to improve the performance of a slow dashboard page. What do you do?

   Profile the page, identify slow queries or API calls, add indexes or caching, and optimize frontend rendering.

Behavioural and HR

1. 9

   Why do you want to work at a SaaS or B2B product company rather than a services company?

   Show interest in building products used by other businesses, solving recurring problems at scale, and continuous learning.

2. 10

   Tell me about a time you worked in a team to complete a project. What was your role?

   Use STAR format, highlight collaboration, communication, and how you handled disagreements or deadlines.

3. 11

   Describe a challenging technical problem you solved. How did you approach it?

   Explain the problem, your thought process, the solution, and what you learned. Keep it concise and honest.

4. 12

   Where do you see yourself in three years in this role?

   Show growth towards owning larger features, mentoring juniors, and deepening expertise in SaaS engineering.

Coding and problem solving

1. 13

   Given a list of API request timestamps, find the busiest minute. How would you solve it?

   Use a hash map to count requests per minute, then find the maximum. Discuss time and space complexity.

2. 14

   Write a function to validate if a string is a valid JSON key (letters, numbers, underscores only).

   Use a regular expression or character loop, handle edge cases like empty string and special characters.

3. 15

   How would you find the first non-repeating character in a string?

   Use a hash map to count frequencies, then iterate to find the first with count one. Mention O(n) time.

4. 16

   Explain how you would reverse a linked list and why it matters in real code.

   Describe iterative pointer manipulation, edge cases, and relate it to understanding data structures in production code.