PayPal Senior Software Engineer Frontend Interview Experience

Overview

The interview process for a Senior Software Engineer Frontend role at PayPal spanned approximately two months, from August 2025 to October 2025. It comprised six distinct rounds designed to evaluate the candidate's technical proficiency and behavioral attributes.

Interview Rounds

The candidate's interview journey included the following stages:

• Round 0: Online HackerRank Assessment (90 minutes):
  • A proctored coding test featuring three questions:
    • Question 1: DSA – String Manipulation (Medium difficulty).
    • Question 2: JavaScript – Class Implementation (Object-oriented programming concepts).
    • Question 3: React UI – Cart Management System (Dynamic cart item updates, state management, real-time UI updates).
• Round 1: DSA Round (45 minutes, extended to 55 minutes):
  • Focused on data structures and algorithms.
    • Question 1: Triangle (Dynamic Programming) - LeetCode Link. A fully working solution that passed all hidden test cases was required.
    • Question 2: Min Stack - LeetCode Link. Implement a stack that supports push, pop, top, and retrieving the minimum element in O(1) time. All operations must pass the hidden test cases.
    • Question 3: Topological Sort (Approach Discussion). Approach explanation, use cases, and implementation using DFS were discussed.
• Round 2: System Design Round (45 minutes):
  • Problem: Design a Payment Gateway System.
  • Discussion covered:
    • Overall system architecture and components.
    • Payment flow between different services.
    • Transaction processing mechanisms.
    • Ledger system implementation for maintaining consistency and traceability.
    • High-level design patterns.
• Round 3: Tech Specialization Round (60 minutes):
  • Part 1: Binary Search Problem (Easy-level DSA question).
  • Part 2: React Internals (Conceptual Discussion).
    • Virtual DOM concepts and benefits.
    • Reconciliation process.
    • Diffing Algorithm mechanics.
    • How React efficiently updates the UI.
  • Part 3: Pseudocode – Diffing Algorithm Implementation.
  • Part 4: Coding – Currency Converter Application.
    • Dropdown selection for different currencies.
    • Dynamic conversion calculations.
    • Real-time updates on user input.