122 questions · from 33 interviews · 2 asked more than once
PayPal interview questions
Every question candidates reported from their PayPal interviews, most frequently asked first. Each links to the write-up it came from, so you can see the round and how it went.
PayPal coding and DSA questions
- 01
Break Sort
Given an array arr of n positive integers, the following operations can be performed 0 or more times: Choose an index i where 0 <= i < n Choose 2 integers, x and y , such that x + y = arr[i] Replace arr[i] with two elements, the two values x and y…
Asked 3 times · From PayPal | SWE Intern 2024 | Virtual | Selected
- 02
Kth Permutation Sequence
The interviewer presented a problem related to finding the Kth permutation sequence, specifically requesting an approach using arrays. After a brief explanation of the problem and test cases, I was given 5 minutes to formulate and articulate my approach.
Hard · Asked 2 times · From PayPal | SWE Intern 2024 | Virtual | Selected
- 03
Steps to Make Array Non-decreasing
Given an integer array, determine the minimum number of steps required to make the array non‑decreasing (i.e., each element is greater than or equal to the previous one).
Medium · From PayPal Senior Software Engineer Interview Experience
- 04
Zigzag Conversion
Convert a given string to a zigzag pattern on a specified number of rows and then read the result line by line to produce a new string.
Medium · From PayPal Senior Software Engineer Interview Experience
- 05
Gas Station
Leetcode question - https://leetcode.com/problems/gas-station/description/
Medium · From Senior Software Engineer (Python) - Paypal
- 06
Articulation Points in a Graph
Given an image, find the number of articulation points (separating vertex).
Hard · From PayPal SSE 6YOE Reject Q4 2025
- 07
Smallest Absolute Difference Pairs
You are given an array of distinct integers. Your task is to find the smallest absolute difference between any two elements in the array. Print all pairs of numbers that have this smallest difference. In each pair, the smallest number comes first. Print the…
Medium · From PayPal SSE 6YOE Reject Q4 2025
- 08
Piles of Boxes
Alex has n piles of boxes with different heights. In each step, Alex can remove any number of boxes from the tallest pile to make its height equal to the next tallest pile. Determine the minimum number of steps needed to make all the piles the same height.…
Medium · From PayPal SSE 6YOE Reject Q4 2025
- 09
Implement Building Interface: School and Hospital Classes
The interface Building includes the following methods: void floorCompleted(int floorNumber) void printStatus(int floorNumber); void printNumberOfFloors(); Develop two classes, School and Hospital, that implement the Building interface. The requirements for…
Easy · From PayPal SSE 6YOE Reject Q4 2025
- 10
Triangle
Given a triangle, find the minimum path sum from top to bottom. For each step, you may move to an adjacent number on the row below. The requirement was a fully working solution passing all hidden test cases using Dynamic Programming.
From PayPal - Senior Software Engineer Frontend Interview Experience
- 11
Min Stack
Implement a stack with push , pop , top , and getMin operations, where getMin retrieves the minimum element in O(1) time. The solution must pass all hidden test cases.
From PayPal - Senior Software Engineer Frontend Interview Experience
- 12
Topological Sort
Explain the approach for Topological Sort without coding.
From PayPal - Senior Software Engineer Frontend Interview Experience
- 13
Remove Minimum Substring for Unique Characters
Given a string, remove the minimum-length substring such that the resulting string contains no duplicate characters. The goal is to maximize the length of the resulting string after removal. Examples: Input: "aabcc" - Output: "ac" (Remove:…
From PayPal - Senior Software Engineer Frontend Interview Experience
- 14
Purchase Optimization (Prefix Sum, Binary Search, Greedy)
The second question in the HackerRank round was related to Purchase Optimization. It involved different patterns related to prefix sum, binary search, and greedy algorithms. Similar problems on LeetCode are: Maximum Number That Sum of the Prices Is Less Than…
- 15
Linked List Manipulation (Create, Remove, Add)
Given a list of values, I was asked to create a Linked List. Subsequently, a tuple was provided containing a value to remove from the Linked List and another value to add at a different place. The task also involved removing all occurrences of a specific…
- 16
Remove All Adjacent Duplicates in String II
You are given a string s and an integer k, a k-duplicate removal consists of choosing k adjacent and equal letters from s and removing them, causing the left and the right side of the deleted substring to concatenate. We repeatedly make k-duplicate removals…
Medium · From Senior Software Engineer (Python) - Paypal
- 17
Singer's Song Range
A new singer is looking for songs to perform. To be able to perform a song all the notes in the song must be within the singer's range, which is given by the lowest and highest notes the singer is able to sing. A note is represented by: - A letter for its…
Medium · From Paypal Karat Interview
- 18
Most Frequent Item in a List (Case-Insensitive, Tie-breaker First Occurrence)
You are given a list of strings, each representing an item that has been selected or used. Write a function that determines which item appears most frequently in the list, along with the total number of times it appears. If there is a tie, return the item…
- 19
Find Nearest Exit in Maze Grid
Given a maze grid, find the nearest exit.
- 20
Single Number
Find the single element that appears only once in an array where all other elements appear twice. Expected solution needed to be time and space optimized.
Easy · From PayPal SDE 3 Interview
- 21
Move Zeroes
Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements. Expected solution needed to be time and space optimized.
Easy · From PayPal SDE 3 Interview
- 22
Design Round Robin Scheduler
Design a Round Robin scheduler. Given a number of tasks and their times, we have to assign available servers to new upcoming tasks and also maintain busy servers.
- 23
Find Palindromic Substring
Find out palindromic sub-string from the input string.
- 24
Remove Adjacent Duplicates in String
Remove adjacent duplicates in input string.
- 25
LRU Cache
Implement a Least Recently Used (LRU) cache data structure.
Medium · From Paypal - SE3 - Feb 2025 Interview Experience
25 more in the PayPal write-ups.
PayPal system design questions
- 01
Web Crawler Design
Design a scalable web crawler that can fetch, parse, and store web pages efficiently while handling issues such as duplicate detection, politeness, and fault tolerance.
- 02
Parking System Design (AI‑enabled entry/exit detection)
Design a parking system that uses AI to automatically detect vehicle entry and exit, handling typical functionalities such as spot allocation, payment processing, and real‑time availability updates.
- 03
Wallet Service Low‑Level Design (Multi‑currency support)
Provide a low‑level design for a digital wallet service that supports multiple currencies, including considerations for transaction handling, currency conversion, data storage, and security.
- 04
Design a Payment System
Question was to design a payment system.
- 05
Design a Configuration Management System
Design a configuration management system to handle deployments across a large number of microservices. Describe the overall system architecture, key components, and how services consume configuration.
- 06
Database Choice for Configuration System
What type of database would you choose for storing configurations and feature flags, and why?
- 07
Database Schema for Configuration System
How would you design the database schema for managing service-level configurations and feature flags?
- 08
Handling Feature Flag Bugs
How would the system handle scenarios where a feature flag introduces a bug in production, and redeploying the service takes significant time?
- 09
Real-time Configuration Updates
How would you ensure real-time or near real-time configuration updates without requiring redeployment?
- 10
Versioning, Auditing, and Rollback of Configurations
How would you manage versioning, auditing, and rollback of configuration changes?
- 11
Design YouTube
I was asked to design Youtube.
From PayPal Interview Experience | SDE2 | Java | Bangalore |
- 12
Design Ride Hailing App Booking Method
Design Ride hailing app booking method.
Hard · From PayPal SSE 6YOE Reject Q4 2025
- 13
Machine Coding: Splitwise
Machine coding for Splitwise application.
Hard · From PayPal SSE 6YOE Reject Q4 2025
- 14
Design a Shopping Website with Cart and Wishlist
Design a complete shopping website, with a particular focus on the architecture and functionality of the 'Cart' and 'Wishlist' features. Follow-up questions also delved into high-level design concepts such as caching, load balancing, and data flow.
- 15
Design a Payment Gateway System
Design a Payment Gateway System, discussing its overall architecture, system components, payment flow between services, transaction processing mechanisms, and ledger system implementation for consistency and traceability. High-level backend design was…
From PayPal - Senior Software Engineer Frontend Interview Experience
- 16
Real-time Amazon Item Price Update System Design
Design a system that provides real-time updates on price changes of Amazon items. I proposed a job-based approach, and to scale it further, I introduced the concept of hot and cold events to efficiently handle updates.
From PayPal Senior Software Engineer (Python) Interview Experience
- 17
System Design: BookMyShow Seating Arrangement LLD
I was asked to design the system for BookMyShow. We covered the High-Level Design (HLD), but the interviewer specifically asked for the Low-Level Design (LLD) for the seating arrangement of a screen.
Hard · From SDE 3(Python) - Paypal || Interview Experience
- 18
Bookmyshow System Design
Design the system for Bookmyshow, focusing on the search of tickets and the payment process.
- 19
Implement Cart Functionality
Design and implement cart functionality, covering both Low-Level Design (LLD) and High-Level Design (HLD) aspects, specifically within a React.js context.
- 20
Design a Ticket Booking System (IRCTC-like)
Design a ticket booking system similar to IRCTC. The interviewer specifically wanted to know how to manage bookings, prevent double booking of seats, and optimize search queries for availability.
- 21
Optimize API Performance and Implement Pagination
A short design conversation focused on optimizing API performance and implementing pagination for large datasets.
- 22
Design Video Streaming Application
The interviewer asked me to design a Video Streaming application. This involved discussing the high-level architecture, key components, and considerations for building such a system.
From PayPal Interview Experience | Jan 2025 | FullStack Developer
- 23
Design and Implement Background Task using WorkManager for Student Object Persistence
How would you design and implement a background task in Android using WorkManager to save a Student object (with ID and name) to SharedPreferences, synchronize it with a remote source, and also persist it using a DAO (database)? Please demonstrate how you…
- 24
Low-Level Design: Notepad App
Design a Notepad application, specifically implementing cursor operations such as up, down, left, right, page up, and page down. Focus on correctness and time complexity.
- 25
System Design: Distributed LRU Cache
Design a Distributed LRU Cache, including discussions on replication, eviction, and cache invalidation strategies.
15 more in the PayPal write-ups.
PayPal behavioural and HR questions
- 01
Tell me about a time where you had done something great apart from your work
Tell me about a time where you had done something great apart from your work.
- 02
Tell me about a time where you had to learn something new & contributed
Tell me about a time where you had to learn something new & contributed.
- 03
Behavioral Questions on Leadership Principles
Behavioral questions centered around leadership principles, including ownership, cross-teams collaboration, handling failure, and resolving architectural conflicts within a team.
- 04
Analyzing Client Feature Requests
Questions around analyzing client feature requests.
- 05
Calculating ROI
Questions around calculating Return on Investment (ROI).
- 06
Innovation and Responsibilities
Questions around innovation and responsibilities in current role.
- 07
End-to-End Feature Planning
Questions around end-to-end feature planning.
- 08
Giving/Receiving Constructive Feedback
Questions around giving/receiving constructive feedback.
- 09
Discuss Current Project Challenges
Discuss current project, challenges faced, and how they were tackled.
- 10
SDLC and Agile Methodology Usage
Discuss how SDLC (Software Development Life Cycle) and Agile methodology are used.
- 11
Integration and Action Items Before Implementation
Discuss how to integrate or code, and what action items will be taken before implementing something.
- 12
Motivation for Leaving Current Job
Explain your reasons for seeking to leave your current employment.
- 13
Job Expectations
Describe your expectations for this role and what you hope to achieve.
PayPal other questions
- 01
Spring Boot Expected Output
Given a basic spring boot, asked for the expected output.
- 02
Caching Header s-maxage Directive
Given a caching header, question was about s-maxage directive.
- 03
Implement Class with Specific Methods
Implement a JavaScript class with several methods according to provided specifications, focusing on object-oriented programming principles in JavaScript.
From PayPal - Senior Software Engineer Frontend Interview Experience
- 04
React Cart Management System UI
Implement functionality for a cart management system in React. Requirements included a sample UI layout, dynamically updating cart items, managing state for total items and quantities, and ensuring the UI reflects changes in real-time.
From PayPal - Senior Software Engineer Frontend Interview Experience
- 05
Pseudocode for React Diffing Algorithm
Write pseudocode for the React Diffing Algorithm. The approach involved a function comparing two DOM trees recursively (DFS-like) and comparing nodes at each level.
From PayPal - Senior Software Engineer Frontend Interview Experience
- 06
React Currency Converter Application
Implement a Currency Converter application in React. Requirements included dynamic conversion based on dropdown selection, updating converted amounts on user input, and proper state management.
From PayPal - Senior Software Engineer Frontend Interview Experience
- 07
Deep Copy with Array Length Update
Implement a function to deep copy an object with a special condition: if any key contains an array, append the array's length to the end of that array in the copied object. Modifying the new object should not affect the original (true deep copy). Example:…
From PayPal - Senior Software Engineer Frontend Interview Experience
- 08
Authorization and Cache-Control MCQs
Two multiple-choice questions were asked, related to Authorization (specifically 401 and 403 errors) and the cache-control header.
- 09
Service vs. IntentService Differences and Use Cases
What are the key differences between Service and IntentService in Android? In which scenarios would you use each one?
- 10
Current Best Practice for Android Long-Running Background Tasks
If a previously recommended background processing component is no longer supported, what is the current best practice for handling long-running tasks in the background?
- 11
UI Component for Large Scrollable Lists
Which UI component is typically used for efficiently displaying large collections of items in a scrollable list?
- 12
Managing and Binding Views in List Components (RecyclerView Pattern)
How does the pattern for efficiently managing and binding views in a list component work? How would you adapt this pattern to display items horizontally or in a grid layout?
- 13
Concept of Deep Linking in Android
What is the concept of deep linking, and how does it enable opening specific screens in an app from a URL?
- 14
Runtime Errors with Code Shrinking/Obfuscation and Reflection
When using code shrinking or obfuscation tools, why might you encounter runtime errors related to missing classes, especially when using reflection, and how can these issues be addressed?
- 15
Optimized Data Pull from External Source
How to pull 1GB of file from an external source, and an optimized way to pull 1 million records of data from an external source.
- 16
API Response Data Extraction
Given an API URL, the task is to make an HTTP request to retrieve the response, and then parse this response to extract data associated with a specific key.
- 17
OOPs: Polymorphism and Its Types
I was asked basic questions about Object-Oriented Programming (OOPs) concepts, specifically focusing on polymorphism and its various types.
- 18
Web Page Development Considerations
Discuss key aspects and considerations one should keep in mind when building a web page.
Easy · From Paypal | Software Engineer 1 | Feb 2022 | Offer
- 19
Class Diagram for Currency Validation
Design a class diagram for validating different currencies, where each currency has its own distinct validation rules.
PayPal interview questions FAQ
What questions are asked in PayPal interviews?
Candidates reported 122 distinct questions across 33 PayPal interviews. 50 coding and DSA questions, 40 system design questions, 13 behavioural and HR questions, 19 other questions.
Which PayPal interview questions are asked most often?
The most repeated are "Break Sort" (3 times), "Kth Permutation Sequence" (2 times).
How difficult are PayPal interview questions?
Of the questions candidates rated, 17% were easy, 52% medium and 31% hard.