Juspay Interviews

🚀 My Juspay SDE Interview Journey "OFF CAMPUS"🚀

I cleared Juspay Technical Interview-I

A few months ago, I applied for the SDE role at Juspay through Internshala

Here's a breakdown of my experience across 5 out of 7 rounds:

1️⃣ Coding Round

Questions on Binary Search (Answer concept),

Graphs

One question I couldn't crack.

Solved 2/3

2️⃣ MCQ Round

Topics included Physics (motion, work-energy), and Math (combinations, permutations, probability),Others

3️⃣ Hackathon Part-A

Problem: Lock-Unlock Tree Upgrade system

Focused on tree-based logic and state transitions

4️⃣ Technical Interview - I (Elimination Round)

Interviewer: Nikita Gupta (2 hours)

Topics covered:

Two live coding rounds via screen sharing

1. Graphs (Disjoint Set Union problem): Rainwater Puddle Formation.....

2. Count Inversion Pairs(brute & optimal via divide & conquer)

Core CS Subjects: OS (scheduling), DBMS, CN, OOPs

React Lifecycle

✅ Cleared this round and received a call from HR the same day!

5️⃣ Hackathon Part-B

Conducted Over Slack Channel

8-hour challenge to make Part-A's solution thread-safe

Implemented with and without mutex using granular locking

Used parallelism & threading for better performance

I prepared overnight and gave it my best shot!

It's been 1.5 weeks ,I haven’t received any further communication from Juspay. Maybe the journey ends here .........

Worst Experience Ever

📌 Opportunity: On-Campus (Open to All Branches)

Position: SDE Intern – Backend

College tier-3

Compensation- 27Lpa

I cleared 5 rounds and finally reached the last round of the interview. This was supposed to be a system design round. The HR had informed me that the interview would consist of questions from OS, DBMS, Computer Science fundamentals, and OOPs—essentially core subjects.

Firstly, the interviewer joined 1.5 hours late. When he finally joined, he said, “Please allow me 2 minutes, I need to use the washroom.” I politely said, “Go ahead, sir.”

When he returned, the first thing he asked was, “Do you know how a toilet flush works?” Honestly, I didn’t know the technical workings, but I had seen some Harpic advertisements on TV. So, I tried to answer by saying, “Sir, I think there's some rubber mechanism that holds water, and when we press the flush button, it releases the water.”

To that, he bluntly replied, “Nahi aata to chup raho” (If you don’t know, keep your mouth shut). I understand that if I didn’t know the answer, I should have stayed quiet—but I thought giving a logical guess or intuition might show I'm trying.

Then he asked me my favorite subject. I replied with a core subject that I enjoy. But he interrupted and said, “Not from your core or engineering subjects.” So I told him, “Sir, space fascinates me.” His counter-question was, “If you're stuck on a planet like Earth, how would you build a spaceship using only Earth’s resources?” I admitted honestly, “Sir, I don't know, I’m from the CSE branch,” especially since at the beginning of the interview he himself said, “If you don’t know the answer, don’t try to answer.”

Next, he shared his screen and showed 8 components. He asked me to build a steam engine using them. Again, I said, “Sorry sir, I don't know.”

He said, “No worries, let’s move to your technical skills.” Then he asked me how a HashMap works in O(1) time complexity. Since I use Java, I explained how HashMaps work both before and after Java 8.

After that, he simply said, your interview is over.”

The next day, 6 students from our college reached the final round. 5 of them received offer letters and PPOs worth 27 LPA. I was the only one rejected.

Below is a summary of the interview process I cleared till Round 5. Thanks.

Note to Juspay (or any senior officials who might see this): Please ensure fairness and professionalism during interviews. This entire process spanned 2 months, and I dedicated myself wholeheartedly—averaging only 5–6 hours of sleep daily. To be treated like this in the final round was deeply disheartening. Students work extremely hard to reach this stage, and interviews should be an opportunity to evaluate—not humiliate.

Round 1: Online Coding Assessment

3 medium to hard-level coding problems (Graphs, Trees) Scored 300/300

16 MCQs based on Physics, Mathematics, and CS Fundamentals

A problem with 3 subtasks (Traditional Tree Space problem) Passed all 10/10 test cases

Round 4: Elimination Interview

Solved 2 DSA problems Interviewer was very supportive and collaborative

Round 5: Hackathon – Part B (Slack-Based)

Walkthrough of Part A solution Discussion on optimization and thread safety using mutex/semaphore and without them Interviewer was very supportive and collaborative

Round 6: System Interview

Questions based on resume,some physics concepts,Probability question and building hardware components from scratch

Final Verdict: ❌ Rejected in the final round

I was presented with the following problem:

Design a thread-safe locking system for a tree. Each node can be locked by a user only if: None of its ancestors or descendants are locked. Locking/Unlocking must be thread-safe (no race conditions). The solution should efficiently support concurrent operations.

The interviewer shared my Hackathon Part A solution that I had submitted previously. They were specifically looking for a solution without using any libraries and wanted me to break down the algorithm and make it thread-safe. My advice for this round is to just stay calm and communicate clearly. That’s all you can do.

The elimination round at Juspay was designed to assess candidates and rule out any unfair practices from the previous Hackathon. During this round, I was required to share my screen and keep my camera on throughout the problem-solving process. I tackled two distinct coding problems. For the second question, I initially faced an edge case, but after presenting my greedy approach, the interviewer seemed satisfied, and I was advanced to the next stage, Hackathon Part B.

I recently had the opportunity to participate in the Juspay SDE Intern hiring process during the summer. It was a challenging yet insightful experience consisting of six rounds. Unfortunately, I couldn’t make it through the final round, but I learned a lot through the process. Here’s a detailed breakdown of my experience:

Round 1: Aptitude Test (Online)

This round had about 300 candidates and lasted 1 hour. It covered OS, CN, Math, and DSA fundamentals. I needed 50% marks to qualify, and the questions were straightforward but required quick thinking.

Round 2: DSA Round

Approximately 180 candidates moved to this 3-hour DSA round. The topics focused on Trees, Graphs, and Strings, with 3 questions in total. I managed to solve two questions out of three (needing 200/300 marks) which helped me qualify for the next round.

Round 3: Hackathon (Part A)

Around 35 candidates participated in this 3-hour hackathon. The main task was to implement Lock, Unlock, and Upgrade functions on a tree structure. It was quite challenging, requiring both efficient and logically sound solutions.

Round 4: Elimination Round (Anti-Cheating Verification)

With about 23 candidates remaining, this 2-hour round served as an integrity check. I had to share my screen and keep my camera on while solving two questions on Hashing and Backtracking. Both questions were of moderate difficulty and required careful thought.

Round 5: Hackathon (Part B)

This was by far the most difficult round, lasting two days for me, though it's usually a single day. Roughly 13 candidates made it here. The tasks included explaining my solution from Part A, improving its time complexity, and implementing a thread-safe solution without using external libraries or atomic variables. Debugging, optimizing, and ensuring thread safety under these constraints truly tested my problem-solving and coding skills under pressure.

Round 6: System Design + Technical Interview

Only about 9 candidates reached this final 2-hour and 15-minute round. It covered OS, CN, CNS, and System Design. The questions were highly conceptual and challenging, probing deep knowledge and optimization techniques. The specific questions I faced were:

1. How does YouTube differentiate between requests from:
   • Two tabs playing YouTube on the same laptop
   • Two different laptops on the same network
   • Two laptops connected to different Networks
2. How are files uploaded to Google Drive and shared between two systems?
3. Compiler vs Interpreter — I was asked to improve the runtime of the following interpreted language code:

   Function f(int c) {
       c++;
       print(c);
       return c;
   }
   main {
       int c=0;
       for(int i = 0; i < 1000; i++) c = f(c);
   }
   

   (The hint provided was that the function call is redundant and can be cached to improve performance).

I felt the questions in the final round were a bit tougher compared to my peers, but it was a great learning experience. This process helped me identify areas for improvement, especially in system design and optimization. I'll work on strengthening these areas and come back stronger next time!