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Explore questions associated with PayPal. Review the source details, then use the workspace for code, notes, and diagrams.
24 questions in the library. A source association does not guarantee a future interview question.
Behavioral and leadership · Coding · Machine learning · Object-oriented design · Practical engineering · System design
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Read-heavy key-value service: unique short-code generation, hot-key caching, redirect semantics.
Companies: PayPal, Amazon, Anduril, Apple +26
API Design · caching · hot-keys · http-redirects
Last reported Oct 2026
Design a scalable authentication system that can handle user registration, login, session management, and secure access control across multiple services.
Companies: PayPal, Airbnb, Upstart
Last reported Jun 2026
Design a payment orchestration layer for a marketplace platform (like Uber or DoorDash) that atomically handles multi-party payment splits across multiple internal services and…
Companies: PayPal, Agoda
Last reported May 2026
Given timestamped accesses per employee, find all employees who made three or more accesses within any one-hour period (accesses exactly 60 minutes apart do not…
Companies: PayPal
Last reported Mar 2026
Design a system migration strategy to transition a payment pricing service from a legacy system to a new modern architecture while maintaining service availability and…
Companies: PayPal
Last reported Mar 2026
Design a price notification system that allows users to track Amazon product prices, subscribe to price drop alerts, and view historical pricing data for items…
Companies: PayPal, Amazon, Meta, Seso Labor
Last reported Feb 2026
Given repeating bus routes and start/target stops, find the minimum number of bus rides required to go from source to target (or -1 if impossible)…
Companies: PayPal, Amazon, Bloomberg, Coupang +3
Array · Breadth-First Search · Hash Table
Last reported Feb 2026
Design a banking system that allows users to create accounts, manage funds (deposits, withdrawals, transfers), check account balances, and perform core banking operations securely.
Companies: PayPal, Anchorage Digital, Capital One, Revolut
Last reported Feb 2026
Given an integer array, find the minimum number of ±1 moves needed to make all elements equal — equivalently, choose a target value that minimizes…
Companies: PayPal
Last reported Jan 2026
Given a line of children with integer ratings, assign each at least one candy so any child with a higher rating than a neighbor gets…
Companies: PayPal, LinkedIn, Marvin
Last reported Oct 2025
Design and implement a notification center system that can handle multiple types of notifications, manage delivery preferences, and provide real-time updates to users.
Companies: PayPal, Amazon
Last reported Oct 2025
Design a real-time gaming leaderboard system that displays global top rankings, user's current rank with surrounding players, and rankings within their friends list, handling…
Companies: PayPal, Airbnb, Google, Meta
System Design
Last reported Oct 2025
Review code that processes payment methods based on business rules, identifying logical issues and implementing new requirements. Analyze program output for given inputs and…
Companies: PayPal, Capital One, Nubank
Last reported Sep 2025
Design a Bank class that maintains 1-indexed account balances and supports transfer, deposit, and withdraw operations; each operation must validate account indices and (for…
Companies: PayPal, Capital One, Coinbase, Okta +1
Last reported Sep 2025
Companies: PayPal, Amazon, Google, Meta
Last reported Sep 2025
Companies: PayPal, Apple, Atlassian, Bloomberg +7
Last reported Sep 2025
Companies: PayPal, Adyen, Anduril, Confluent +5
Last reported Sep 2025
Companies: PayPal
Model Evaluation · Supervised Learning
Companies: PayPal
Given an array of integers, return the length of the longest strictly increasing subsequence; the core challenge is to compute this efficiently—naive DP is O(n^2)…
Companies: PayPal
Array · Binary Search · Dynamic Programming · Longest Increasing Subsequence
Arrange the characters of a string into a zigzag pattern across numRows and then read the rows sequentially to produce the converted string. The core…
Companies: PayPal, Amazon, Bloomberg, Google +1
String