PayPal Backend Engineer Interview Questions

The questions to prepare for a PayPal Backend Engineer interview. Questions from real interview reports rank first. Updated weekly.

Tests your ability to implement and reason about a basic string algorithm.

Palindrome Detection Follow-Ups

Medium

Tests your ability to extend a baseline solution and handle progressively harder variations.

Strings

PayPal

Maintainable and Scalable Code

Medium

Tests engineering practices that support long-term evolution, readability, and performance.

code qualityDynamic ProgrammingAlgorithms

PayPal

More Coding questions with a free account

Design a real-time fraud scoring system for card transactions with strict latency, delayed labels, and high availability requirements.

Synchronous vs Asynchronous Processing

Medium

Assesses your understanding of execution models and their impact on system behavior and performance.

asynchronous

PayPal

Handling Massive Transaction Spikes

Hard

Tests your ability to plan for load spikes using scaling, buffering, and resilience techniques.

system designtransaction volumescalability

PayPal

More System Design questions with a free account

Create a free account to unlock this list and practice real interview questions.

More Behavioral & Leadership questions with a free account

Optimizing Slow SQL Queries

Medium

Tests your ability to diagnose and improve SQL performance using query and indexing strategies.

Window FunctionsJoinsAggregations

PayPal

Designing Database Schemas

Medium

Tests data modeling skills, normalization, indexing, and performance considerations for production systems.

Trade-offsRisk AssessmentScope Management

PayPal