Barclays Interview Experience

Hello, I am Onkar Dhanaji Patil, currently pursuing B.Tech in Computer Engineering, Batch of 2026. I recently appeared for an interview process and would like to share my experience.

Round 1: Online Assessment (OA)

1. 1 DSA Coding Question :- Smallest Generated String

2. 1 SQL Query

3. 12 MCQs (Core Subjects + Aptitude)

Round 2 : Technical Interview (~1 hr 20 mins)

This round focused heavily on core subjects, problem-solving, and system thinking.

1. Introduction

• Started with an introduction.

• Since I mentioned in introduction scoring 100/100 in Maths in 12th, interviewer asked:

  1. To draw a sin curve

  2. Then asked about shifting the curve and changes in equation (sin(x + α))

  3. Asked: What is cosine (basic definition)

2. Core Computer Science

• Compiler Design:

  1. Asked about 6 phases of compiler

  2. I answered partially (syntax, semantic, Lexical Analysis)

3. Database & SQL

• Asked current subjects in syllabus → I mentioned Information Retrieval (I want to divert to my strong area SQL & Database)

• Given a stored procedure and asked to optimize it : Basically it was the use of index (on/off) during insert/update strategy .

• Difference between TRUNCATE vs DELETE

• Explain Concepts Cursor and its usage in your projects.

4. Project Deep Dive

• Asked to explain one of your project.

• Questions on : Collaboard project , Database used (Convex DB)

5. DSA & Complexity

• What is Time Complexity ?

• What is need of Time Complexity ?

• Language used for DSA → C++

• Why C++ for DSA and not Java ?

• Why C++ is faster than Java ?

• Features of Java over C++

• Given a code (heap sort):

  1. Asked to write and analyze

  2. Best, Worst, Average case complexity

7. System Design

• Asked to design a system:

  1. Take user credentials (name, password)

  2. Store with current time

  3. Handle server reboot scenario

• I explained from a database trigger perspective

• Interviewer expected CI/CD pipeline-based solution

• I mentioned I was not familiar with DevOps

9. OS & Networking

• Asked about : SSH and Network Protocols , Basic Linux commands

10. LLD & Design Patterns

• Since I mentioned exploring LLD:

  1. Asked about Design Patterns ( Abstract Factory, Adapter, Bridge, Factory Method, Singleton )

  2. Where I used them in projects

Duration:

~1 hour 20 minutes

Round 3 : Technical Interview + HR  (~45–50 mins)

This round was completely resume-based, with deep discussion on projects &concepts and DSA.

1. Introduction & Background

• Started with a brief introduction.

• Asked about my experience and technologies I have worked on.

2. Technical Discussion

• Since the interviewer was working on TypeScript, she asked detailed questions:

  1. Difference between interface vs type

  2. Concept of decorators

• Asked : Why have you chosen Next.js & TypeScript for your project?

3. Project Discussion

• All projects were discussed in detail.

• I demonstrated my project using my mobile and explained the complete flow.

• Questions included:

  1. Features implemented

  2. My role in the project

4. Core Concepts

• Explained OOP pillars and where I used them in my project.

• Asked about SOLID principles and their usage in real projects.

• Use of SOLID principles in my projects

5. DSA & Problem Solving

• Asked about my DSA preparation and ratings on Leetcode and Codechef.

• Question:

  1. How to search an element in a Binary Tree , Explain all possible ways

  2. Explained approaches: DFS & BFS

  3. She ask question of mirror image of tree ( Leetcode 101 )

• Performed a dry run of Level Order Traversal code

6. Database & System Design

• Asked to design the database schema of my project:

  • Fields, relationships, foreign keys

  • Draw and Explained ER Diagram (NSS Treasure Project)

• Asked about:

  • ACID properties and how I handled them

7. Extracurricular & Leadership

Asked about NSS (National Service Scheme):

1. My role as Data Head

2. Explained responsibilities and work

3. Shared experience of managing a team during camps

8. Behavioral & Practical Questions

Asked:

1. How I handled risks in my project

2. Whether I have learned new technologies under tight deadlines

Duration:

~47 minutes

Verdict: Selected ✅

Key Learnings:

• Whatever you mention in your resume, you should know every word in detail.

• Be very strong in your projects (end-to-end understanding)

• Prepare core CS subjects (Compiler, OS, SQL, IR) thoroughly

• Expect cross-questioning and deep discussions

• Have at least basic knowledge of DevOps concepts (CI/CD)

• Be ready to justify technology choices