Quixy Software Engineer Interview: Rounds, Questions and Preparation

What the job involves

As a Software Engineer at an Indian SaaS or B2B product company, you will build and maintain features for multi-tenant web applications used by business customers. Day to day you write code, fix bugs, participate in code reviews, and work with product and QA teams to ship reliable software. You may also work on APIs, integrations, and performance improvements for enterprise clients.

Role and Technical Knowledge

1. 1

   What is a multi-tenant SaaS application and how does it differ from a single-tenant one?

   Explain that multi-tenant shares infrastructure and data across customers with logical isolation, while single-tenant gives each customer a separate instance. Mention benefits like cost efficiency and challenges like data security.

2. 2

   How would you design a REST API for a B2B product that manages customer projects?

   Cover resource naming (e.g., /projects), HTTP methods (GET, POST, PUT, DELETE), status codes, authentication (e.g., API keys or OAuth), and pagination for large datasets.

3. 3

   Explain the difference between SQL and NoSQL databases. When would you choose one over the other for a SaaS product?

   Discuss structured vs flexible schemas, scaling (vertical vs horizontal), and use cases. For SaaS, SQL is often preferred for transactional data, while NoSQL suits unstructured or high-volume data.

4. 4

   What are the key considerations for ensuring data security in a B2B SaaS product?

   Mention encryption at rest and in transit, role-based access control, regular audits, and compliance with standards like ISO 27001 or SOC 2.

Practical Scenarios

1. 5

   A customer reports that a feature is slow for large datasets. How would you debug and improve performance?

   Outline steps: reproduce the issue, profile the code, check database queries and indexes, optimize algorithms, and consider caching or pagination.

2. 6

   You need to add a new feature that integrates with a third-party API. How do you approach it?

   Discuss reading API docs, handling authentication, error handling, rate limiting, and writing tests. Mention using mock servers for development.

3. 7

   How would you handle a situation where you accidentally pushed a bug to production?

   Show ownership: roll back the change, notify the team, fix the bug with a hotfix, and add tests to prevent recurrence. Emphasize learning and communication.

4. 8

   Describe how you would implement user authentication and authorization for a B2B product with different user roles.

   Cover session management or JWT, role-based access control (RBAC), and secure password storage (hashing with salt). Mention OAuth for third-party logins.

Behavioural and HR

1. 9

   Why do you want to work in a SaaS product company like Quixy rather than a services company?

   Show interest in building products, solving recurring problems for many customers, and working in a fast-paced environment. Mention desire to learn and grow with the product.

2. 10

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

   Use STAR method: describe the situation, task, action, and result. Highlight collaboration, communication, and your specific contribution.

3. 11

   How do you handle feedback or criticism on your code?

   Demonstrate openness to learning, willingness to improve, and ability to separate personal feelings from professional growth. Give an example if possible.

4. 12

   Where do you see yourself in the next two years in terms of technical and career growth?

   Align your goals with the company's needs: becoming a strong contributor, learning new technologies, and taking on more responsibility. Avoid vague answers.

Coding and Problem Solving

1. 13

   Write a function to find the first non-repeating character in a string.

   Use a hash map to count frequencies, then iterate to find the first character with count 1. Discuss time and space complexity.

2. 14

   Given an array of integers, find two numbers that add up to a target sum.

   Explain the brute force approach and then optimize using a hash map for O(n) time. Mention edge cases like no solution or multiple solutions.

3. 15

   How would you reverse a linked list?

   Describe iterative and recursive approaches. For iterative, use three pointers (prev, current, next) and update links. Analyze time and space complexity.

4. 16

   Explain how you would detect a cycle in a linked list.

   Use Floyd's cycle-finding algorithm (tortoise and hare) with two pointers moving at different speeds. Mention that if they meet, a cycle exists.