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PayPal System Design Interview Questions

A comprehensive prep guide to PayPal System Design Interview Questions. Strengthen your understanding of distributed systems and excel by practicing with real-world interview questions.

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PayPal engineers design systems that are resilient, secure, and capable of handling millions of transactions per second. If you're targeting a backend or infrastructure role at PayPal, you’ll need to demonstrate your ability to reason through trade-offs in distributed systems, especially within the context of real-time financial operations. This course focuses on PayPal-specific System Design questions inspired by real production systems. You’ll go beyond generic architectures and explore design problems that mirror the financial, regulatory, and scale challenges PayPal engineers solve every day. Using the RESHADED framework, each question helps you break down high-level goals into modular components, prioritizing availability, data integrity, latency, and security. By the end, you’ll not only be ready to interview at PayPal—you’ll have a deep understanding of how to build financial systems that operate reliably at a global scale.

PayPal engineers design systems that are resilient, secure, and capable of handling millions of transactions per second. If you'...Show More

WHAT YOU'LL LEARN

A structured, modular approach to PayPal System Design Interviews, tailored for high-impact roles.

Techniques to architect complex payment and transaction systems using scalable, microservice-based building blocks

The skills to analyze real-world requirements and constraints, critical for designing infrastructure at PayPal scale

Insight into common System Design questions asked in PayPal interviews, and strategies to confidently navigate them

How to apply systematic thinking to fintech-specific problems, including payment routing, fraud detection, and user authentication

A deeper understanding of how large-scale web services (including financial platforms like PayPal) are built and maintained

A robust, repeatable method for solving novel design problems, with this course serving as a blueprint for PayPal-style system thinking

A structured, modular approach to PayPal System Design Interviews, tailored for high-impact roles.

Content

180 Lessons140 Quizzes

System Design Interviews

5 Lessons

Getting Ready for the System Design Interview

Key Concepts to Prepare for the System Design Interview

Resources to Prepare for a System Design Interview

The Do’s and Don’ts of the System Design Interview

Let AI Evaluate your System Design Interview Preparation

Introduction

2 Lessons

Introduction to Modern System Design

Course Structure for Modern System Design

Abstractions

4 Lessons

Non-functional System Characteristics

6 Lessons

Back-of-the-envelope Calculations

2 Lessons

Building Blocks

1 Lessons

Domain Name System

2 Lessons

Load Balancers

3 Lessons

Databases

5 Lessons

10.

Key-value Store

5 Lessons

11.

Content Delivery Network (CDN)

7 Lessons

12.

Sequencer

3 Lessons

13.

Distributed Monitoring

3 Lessons

14.

Monitor Server-side Errors

3 Lessons

15.

Monitor Client-side Errors

2 Lessons

16.

Distributed Cache

6 Lessons

Distributed Cache System

Mock Interview

Premium

17.

Distributed Messaging Queue

7 Lessons

18.

Pub-sub

3 Lessons

Pub-Sub

Mock Interview

Premium

19.

Rate Limiter

5 Lessons

20.

Blob Store

6 Lessons

Blob Store

Mock Interview

Premium

21.

Distributed Search

6 Lessons

22.

Distributed Logging

3 Lessons

23.

Distributed Task Scheduler

5 Lessons

24.

Sharded Counters

4 Lessons

25.

Concluding the Building Blocks Discussion

4 Lessons

26.

Design YouTube

6 Lessons

TikTok

Mock Interview

Premium

27.

Design Quora

5 Lessons

28.

Design Google Maps

6 Lessons

29.

Design a Proximity Service / Yelp

5 Lessons

30.

Design Uber

7 Lessons

Uber Eats

Mock Interview

Premium

31.

Design Twitter

6 Lessons

32.

Design Newsfeed System

4 Lessons

33.

Design Instagram

5 Lessons

NewsFeed

Mock Interview

Premium

34.

Design a URL Shortening Service / TinyURL

6 Lessons

35.

Design a Web Crawler

5 Lessons

36.

Design WhatsApp

6 Lessons

Facebook Messenger

Mock Interview

Premium

37.

Design Typeahead Suggestion

7 Lessons

38.

Design a Collaborative Document Editing Service / Google Docs

5 Lessons

39.

Spectacular Failures

4 Lessons

ChatGPT

Mock Interview

Premium

40.

Concluding Remarks

1 Lessons

Certificate of Completion

Showcase your accomplishment by sharing your certificate of completion.

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Hands-on Learning Powered by AI

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Personalized Interview Prep

Skip the LeetCode grind with a custom roadmap that adapts to your goals. Hands-on practice for Coding Interviews, System Design, and more.

Mock Interviews

Test your skills in a simulated interview setting. Receive personalized feedback based on your performance. Available for Coding Interviews, System Design, and more.

AI Prompt

Build prompt engineering skills. Practice implementing AI-informed solutions.

Code Feedback

Evaluate and debug your code with the click of a button. Get real-time feedback on test cases, including time and space complexity of your solutions.

Explain with AI

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AI Code Mentor

AI Code Mentor helps you quickly identify errors in your code, learn from your mistakes, and nudge you in the right direction — just like a 1:1 tutor!

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Frequently Asked Questions

What is the structure of the System Design interview at PayPal?

PayPal’s System Design interviews test your ability to design secure, scalable, and high-performance systems, often centered on payment processing and financial reliability. Overall, candidates are expected to design solutions grounded in real-world applications.

Are PayPal System Design interviews hard?

Yes. They’re challenging and comparable to those at Google or Amazon, focusing heavily on secure, scalable financial systems.

How do I study for the PayPal System Design interview?

Start with System Design fundamentals, especially for financial systems. Practice common scenarios and review PayPal’s engineering blog for real-world insights.

What are the common mistakes people make in a System Design interview at PayPal?

Common mistakes include neglecting security, skipping scalability trade-offs, overlooking financial reliability, and jumping into solutions without clarifying requirements first.