Physics Wallah Staff Backend Engineer | September 2026

I interviewed for a Staff Backend Engineer role at Physics Wallah in September 2026.

Background

• Company: Physics Wallah

• Role: Staff Backend Engineer

• YOE: 7+

• Current Organization: Small Startup

• College: Tier-1

• Current Compensation: ₹55L Base + ₹10L Bonus + ₹20L ESOPs/year

How the Interview Process Went

Initial Screen - Hiring Manager

The process started with a conversation with the Hiring Manager.

Discussed my current project, my responsibilities, the role I was interviewing for, and the team structure. This was mainly an introductory discussion before moving into the technical rounds.

Round 1 - DSA

The first technical round was focused on problem solving.

The problem was based on finding the Longest Increasing Subsequence in an integer array.

The discussion covered the approach and how to optimize the solution.

Round 2 - System Design 1

The next round moved into system design.

The problem was to design an experimentation / feature flag system capable of handling around 2 million requests per minute for variant evaluation.

Some of the key points discussed were:

• The system would be called by internal services, although using a client library could provide a better architecture.

• Consistent hashing could be used for assigning users to different variants.

• Changes would need to be propagated efficiently to client libraries.

• We discussed using CDC (Change Data Capture) as part of the propagation mechanism.

The focus was largely on scalability, consistency, and how the system would behave at high request volumes.

Round 3 - System Design 2

The third round was another HLD discussion, this time around designing an E-book Store service.

The interesting part of the problem was the scale: around 6 million concurrent reads for a book during its launch.

The system needed to support:

• Users adding and purchasing books

• Free as well as paid books

• Preview pages for books

• Restricting access to the actual content unless the user had purchased the book

• Preventing users from downloading the complete book locally

The discussion therefore went beyond basic CRUD and focused on high read traffic, access control, content delivery, and scalability.

Round 4 - Senior VP

The final round was with a Senior VP and was largely based on my previous work.

We went deep into one of the most technically challenging projects I had worked on. The discussion focused on:

• Major technical decisions I had made

• How the system could be optimized for significantly higher scale

• Database-related decisions

• Networking considerations

• SQL vs. NoSQL and when to choose each

• The reasoning and trade-offs behind different architectural choices

This round was less about solving a predefined design problem and more about understanding how I approach real-world engineering decisions at scale.

Final Outcome

I was selected for the Staff Backend Engineer role.