The Interview Process

There were three technical rounds, followed by an HR discussion:

  • Round 1: Technical — DSA + Frontend
  • Round 2: Technical — DSA + Fullstack
  • Round 3: Technical + Managerial — System Design

I will cover the third round in detail in this article.

Round 3: System Design

This round delved deep into my technical skills and experience, focusing on the specifics of my resume. The hiring manager explored the technologies and challenges I had encountered in past projects, aiming to understand my problem-solving approach and my ability to articulate both high-level and low-level system perspectives.

1. Resume Walkthrough

We began by discussing my resume, providing an opportunity to highlight my actual contributions. The interviewer inquired about several projects, emphasizing the challenges I faced and the solutions I implemented. The discussion centered not just on what I did, but also on the reasoning behind my decisions and the technical problems I addressed.

To illustrate the architecture of one of my projects, I used Excalidraw.

2. System Design Problem

Following the resume discussion, we moved on to a system design problem.

I utilized the RADIO framework to structure my thought process. Starting with a High-Level Design (HLD), I outlined the overall system flow and the interactions between components. As we delved deeper, I transitioned into Low-Level Design (LLD), particularly focusing on the interaction between the front end (specifically React components) and the backend APIs.

A critical aspect was distinguishing between Functional and Non-Functional Requirements, explaining which features I would prioritize, especially concerning performance, scalability, and fault tolerance.

Specific areas of interest included:

  • Client-Server Interaction: Discussing the choice between polling and WebSockets.
  • Infrastructure Management: Addressing API gateways, load balancing, and rate limiting.
  • Database Optimization: Covering indexing, query optimization, and sharding strategies.

3. Performance Optimization

With the system design established, we shifted focus to performance optimizations. This segment was both engaging and challenging, as it involved strategies to enhance user experience and ensure system resilience under high traffic conditions.

Key performance optimization strategies discussed:

  • Lazy Loading: Loading resources only when necessary to improve initial page load times.
  • Resource Hinting: Preloading critical resources (e.g., fonts, scripts, images) to expedite perceived load times.
  • Reducing Requests: Minimizing HTTP requests by bundling assets (JS, CSS) and employing techniques like image compression or serving images in modern formats (e.g., WebP).
  • Render Optimization: Reducing render-blocking resources by using async or defer for script loading and implementing CSS-in-JS to decrease the number of CSS files, thereby enhancing initial render performance and preventing unnecessary reflows/repaints.
  • Virtualization of Large Lists: Implementing list virtualization for applications with extensive datasets or lengthy lists (such as social media feeds or tables) to render only the visible portion, conserving memory and accelerating rendering.
  • Improving Lighthouse Metrics: Emphasizing metrics like First Contentful Paint (FCP), Largest Contentful Paint (LCP), and Time to Interactive (TTI) to assess and improve performance.

4. Security Considerations

The interview then transitioned to security aspects, focusing on common web vulnerabilities and their prevention. We discussed protecting a web application against threats like Cross-Site Scripting (XSS) and Cross-Site Request Forgery (CSRF). Practical solutions included:

  • Sanitizing User Input: Preventing malicious scripts (XSS) by sanitizing user inputs.
  • Using Tokens: Implementing tokens to prevent unauthorized requests (CSRF).

5. Behavioral Questions

The final segment of the interview comprised behavioral questions, assessing my approach to teamwork, problem-solving, and handling challenging situations. These situational questions were akin to those typically encountered in managerial rounds.

Key Takeaways

  • Know Your Projects Inside Out: Be prepared to discuss your projects in detail, including the challenges faced and the decisions made.
  • Structure Your Thoughts: Utilize frameworks like RADIO to organize your approach to system design problems.
  • Prioritize Performance and Security: Demonstrate awareness of performance optimization techniques and security best practices.
  • Be Ready for Behavioral Questions: Reflect on past experiences to effectively address situational questions.

Note: This article is based on my personal experience and may not represent the exact process for all candidates.