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LLM Fundamentals58 questions · 7 free Prompt Engineering55 questions · 7 free LLM APIs & Integration52 questions · 7 free RAG56 questions · 6 free Embeddings & Vector Databases56 questions · 7 free AI Agents54 questions · 7 free Model Context Protocol56 questions · 7 free Fine-Tuning & Model Customization56 questions · 7 free AI Evals & Observability57 questions · 7 free AI Security & Guardrails55 questions · 7 free Open-Source & Local LLMs55 questions · 7 free AI System Design54 questions · 7 free

AI Coding Assistants51 questions · 7 free Agentic Coding Workflows51 questions · 7 free Context Engineering49 questions · 7 free AI in Engineering Teams49 questions · 7 free

Big-O & Complexity Analysis57 questions · 7 free Arrays, Strings & Hash Tables85 questions · 11 free Linked Lists, Stacks & Queues78 questions · 11 free Trees, BSTs & Heaps76 questions · 11 free Graphs60 questions · 9 free Sorting, Searching & Recursion61 questions · 10 free Object-Oriented Programming90 questions · 9 free Operating Systems56 questions · 7 free Concurrency & Multithreading54 questions · 7 free Networking for Developers51 questions · 7 free Git & Version Control54 questions · 7 free

JavaScript126 questions · 16 free TypeScript102 questions · 16 free HTML587 questions · 14 free CSS3110 questions · 15 free React103 questions · 15 free Redux84 questions · 16 free Next.js95 questions · 14 free Angular95 questions · 13 free Vue.js105 questions · 15 free GraphQL60 questions · 9 free Vite & Webpack89 questions · 15 free

Java89 questions · 13 free Spring Boot74 questions · 10 free Hibernate38 questions · 5 free Python52 questions · 7 free Django47 questions · 7 free FastAPI46 questions · 6 free Flask56 questions · 8 free Node.js57 questions · 8 free Express.js44 questions · 6 free Nest.js44 questions · 6 free C#112 questions · 14 free ASP.NET Core62 questions · 9 free Entity Framework Core52 questions · 7 free Golang67 questions · 10 free PHP78 questions · 11 free Laravel50 questions · 7 free Ruby85 questions · 12 free Ruby on Rails65 questions · 9 free C++59 questions · 8 free Apache Kafka37 questions · 5 free

SQL Fundamentals41 questions · 6 free Database Design35 questions · 5 free PostgreSQL36 questions · 5 free MySQL35 questions · 5 free SQL Server35 questions · 5 free MongoDB52 questions · 7 free Redis26 questions · 3 free DynamoDB35 questions · 5 free Cassandra35 questions · 5 free Elasticsearch39 questions · 5 free

Swift51 questions · 7 free SwiftUI & UIKit80 questions · 11 free Kotlin41 questions · 6 free Android & Jetpack Compose109 questions · 14 free Flutter49 questions · 7 free React Native51 questions · 7 free

Software Architecture42 questions · 6 free Design Patterns45 questions · 6 free API Design92 questions · 18 free Microservices72 questions · 9 free Distributed Systems Fundamentals51 questions · 7 free Caching22 questions · 3 free Load Balancing26 questions · 3 free Rate Limiting & Throttling22 questions · 3 free Sharding & Replication51 questions · 6 free Messaging & Event-Driven Architecture95 questions · 13 free Domain-Driven Design38 questions · 5 free Observability & Monitoring167 questions · 22 free Serverless Architecture35 questions · 5 free

Software Testing125 questions · 18 free Unit Testing & TDD91 questions · 10 free API Testing21 questions · 3 free Performance Testing43 questions · 7 free Selenium32 questions · 4 free Playwright49 questions · 7 free Cypress39 questions · 5 free Jest49 questions · 7 free JUnit 5 & Mockito51 questions · 7 free PyTest33 questions · 4 free

Docker45 questions · 5 free Kubernetes90 questions · 13 free CI CI/CD Pipelines86 questions · 10 free Terraform37 questions · 4 free Ansible34 questions · 7 free Linux58 questions · 7 free Bash & Shell Scripting40 questions · 4 free

Web Security & OWASP Top 1071 questions · 8 free Authentication & Authorization70 questions · 6 free Cryptography & TLS46 questions · 7 free DevSecOps & Cloud Security206 questions · 29 free

Machine Learning Fundamentals36 questions · 5 free Classical ML Algorithms56 questions · 8 free Data Preparation & Feature Engineering58 questions · 8 free Model Evaluation & Validation43 questions · 6 free Statistics & Experimentation45 questions · 6 free Deep Learning & Neural Networks48 questions · 7 free MLOps & Model Deployment42 questions · 6 free

By role

Stacks & frameworks

MEAN

MongoDB, Express, Angular, Node.js

MongoDB52 questions · 7 free Express.js44 questions · 6 free Angular95 questions · 13 free Node.js57 questions · 8 free TypeScript102 questions · 16 free

MERN

MongoDB, Express, React, Node.js

MongoDB52 questions · 7 free Express.js44 questions · 6 free React103 questions · 15 free Node.js57 questions · 8 free Redux84 questions · 16 free

LAMP

Linux, Apache, MySQL, PHP

Linux58 questions · 7 free MySQL35 questions · 5 free PHP78 questions · 11 free Laravel50 questions · 7 free

Django

Python Full-Stack Development

Python52 questions · 7 free Django47 questions · 7 free PostgreSQL36 questions · 5 free Redis26 questions · 3 free Docker45 questions · 5 free

Ruby on Rails

Convention over Configuration

Ruby85 questions · 12 free Ruby on Rails65 questions · 9 free PostgreSQL36 questions · 5 free Redis26 questions · 3 free

Serverless on AWS

Serverless Architecture on AWS

Serverless Architecture35 questions · 5 free API Design92 questions · 18 free DynamoDB35 questions · 5 free Node.js57 questions · 8 free

Cross-cutting topics 30 topics

Interviewers also test these - they're common to every stack, whichever one you picked above.

Topics in Computer Science Fundamentals Browse all of Computer Science Fundamentals

Big-O & Complexity Analysis Arrays, Strings & Hash Tables Linked Lists, Stacks & Queues Trees, BSTs & Heaps Graphs Sorting, Searching & Recursion Operating Systems Concurrency & Multithreading Networking for Developers Git & Version Control

Topics in System Design Concepts Browse all of System Design Concepts

Software Architecture Design Patterns Microservices Distributed Systems Fundamentals Caching Load Balancing Rate Limiting & Throttling Sharding & Replication Messaging & Event-Driven Architecture Domain-Driven Design Observability & Monitoring

Topics in Testing Browse all of Testing

Software Testing Unit Testing & TDD API Testing Performance Testing

Topics in Security Browse all of Security

Web Security & OWASP Top 10 Authentication & Authorization Cryptography & TLS

Topics in Database Technologies Browse all of Database Technologies

SQL Fundamentals Database Design

Flutter Mobile

Flutter Cross-Platform Mobile Development

Flutter49 questions · 7 free API Design92 questions · 18 free

Cross-cutting topics 31 topics

Interviewers also test these - they're common to every stack, whichever one you picked above.

Topics in System Design Concepts Browse all of System Design Concepts

Software Architecture Design Patterns Microservices Distributed Systems Fundamentals Caching Load Balancing Rate Limiting & Throttling Sharding & Replication Messaging & Event-Driven Architecture Domain-Driven Design Observability & Monitoring Serverless Architecture

Topics in Computer Science Fundamentals Browse all of Computer Science Fundamentals

Big-O & Complexity Analysis Arrays, Strings & Hash Tables Linked Lists, Stacks & Queues Trees, BSTs & Heaps Graphs Sorting, Searching & Recursion Operating Systems Concurrency & Multithreading Networking for Developers Git & Version Control

Topics in Testing Browse all of Testing

Software Testing Unit Testing & TDD API Testing Performance Testing

Topics in Security Browse all of Security

Web Security & OWASP Top 10 Authentication & Authorization Cryptography & TLS

Topics in Database Technologies Browse all of Database Technologies

SQL Fundamentals Database Design

Spring Boot

Enterprise Java Development

Java89 questions · 13 free Spring Boot74 questions · 10 free PostgreSQL36 questions · 5 free Redis26 questions · 3 free Apache Kafka37 questions · 5 free Docker45 questions · 5 free Kubernetes90 questions · 13 free

.NET

Microsoft Ecosystem

C#112 questions · 14 free ASP.NET Core62 questions · 9 free Entity Framework Core52 questions · 7 free SQL Server35 questions · 5 free

Vue

Vue.js, Vite, TypeScript, Tailwind, Node.js

Vue.js105 questions · 15 free Vite & Webpack89 questions · 15 free TypeScript102 questions · 16 free Node.js57 questions · 8 free

Go Backend

Golang, gRPC, PostgreSQL, Redis, RabbitMQ

Golang67 questions · 10 free API Design92 questions · 18 free PostgreSQL36 questions · 5 free Redis26 questions · 3 free Messaging & Event-Driven Architecture95 questions · 13 free Docker45 questions · 5 free

Cross-cutting topics 30 topics

Interviewers also test these - they're common to every stack, whichever one you picked above.

Topics in Computer Science Fundamentals Browse all of Computer Science Fundamentals

Big-O & Complexity Analysis Arrays, Strings & Hash Tables Linked Lists, Stacks & Queues Trees, BSTs & Heaps Graphs Sorting, Searching & Recursion Operating Systems Concurrency & Multithreading Networking for Developers Git & Version Control

Topics in System Design Concepts Browse all of System Design Concepts

Software Architecture Design Patterns Microservices Distributed Systems Fundamentals Caching Load Balancing Rate Limiting & Throttling Sharding & Replication Domain-Driven Design Observability & Monitoring Serverless Architecture

Topics in Testing Browse all of Testing

Software Testing Unit Testing & TDD API Testing Performance Testing

Topics in Security Browse all of Security

Web Security & OWASP Top 10 Authentication & Authorization Cryptography & TLS

Topics in Database Technologies Browse all of Database Technologies

SQL Fundamentals Database Design

FastAPI

Python, FastAPI, SQLAlchemy, PostgreSQL

Python52 questions · 7 free FastAPI46 questions · 6 free PostgreSQL36 questions · 5 free Redis26 questions · 3 free Docker45 questions · 5 free

React Native

React, TypeScript, Redux, Firebase

React Native51 questions · 7 free React103 questions · 15 free TypeScript102 questions · 16 free Redux84 questions · 16 free

iOS Native

Swift, SwiftUI, UIKit, Firebase

Swift51 questions · 7 free SwiftUI & UIKit80 questions · 11 free

Android Native

Java, Jetpack Compose, Firebase

Kotlin41 questions · 6 free Android & Jetpack Compose109 questions · 14 free

DevOps / Platform

Docker, Kubernetes, Terraform, CI/CD

Docker45 questions · 5 free Kubernetes90 questions · 13 free Terraform37 questions · 4 free CI CI/CD Pipelines86 questions · 10 free Observability & Monitoring167 questions · 22 free

Cross-cutting topics 31 topics

Interviewers also test these - they're common to every stack, whichever one you picked above.

Topics in Computer Science Fundamentals Browse all of Computer Science Fundamentals

Big-O & Complexity Analysis Arrays, Strings & Hash Tables Linked Lists, Stacks & Queues Trees, BSTs & Heaps Graphs Sorting, Searching & Recursion Operating Systems Concurrency & Multithreading Networking for Developers Git & Version Control

Topics in System Design Concepts Browse all of System Design Concepts

Software Architecture Design Patterns API Design Microservices Distributed Systems Fundamentals Caching Load Balancing Rate Limiting & Throttling Sharding & Replication Messaging & Event-Driven Architecture Domain-Driven Design Serverless Architecture

Topics in Testing Browse all of Testing

Software Testing Unit Testing & TDD API Testing Performance Testing

Topics in Security Browse all of Security

Web Security & OWASP Top 10 Authentication & Authorization Cryptography & TLS

Topics in Database Technologies Browse all of Database Technologies

SQL Fundamentals Database Design

AI Engineer

LLMs, RAG, Agents, Evals

LLM Fundamentals58 questions · 7 free Prompt Engineering55 questions · 7 free LLM APIs & Integration52 questions · 7 free RAG56 questions · 6 free AI Agents54 questions · 7 free AI Evals & Observability57 questions · 7 free

AI-Powered Developer

Claude Code, Copilot, Agentic Workflows

AI Coding Assistants51 questions · 7 free Agentic Coding Workflows51 questions · 7 free Context Engineering49 questions · 7 free AI in Engineering Teams49 questions · 7 free

Core SWE Interview Prep

Data structures, algorithms, OS, concurrency, networking, git

Big-O & Complexity Analysis57 questions · 7 free Arrays, Strings & Hash Tables85 questions · 11 free Linked Lists, Stacks & Queues78 questions · 11 free Trees, BSTs & Heaps76 questions · 11 free Graphs60 questions · 9 free Sorting, Searching & Recursion61 questions · 10 free Operating Systems56 questions · 7 free Concurrency & Multithreading54 questions · 7 free Networking for Developers51 questions · 7 free Git & Version Control54 questions · 7 free API Design92 questions · 18 free Distributed Systems Fundamentals51 questions · 7 free

Cross-cutting topics 20 topics

Interviewers also test these - they're common to every stack, whichever one you picked above.

Topics in System Design Concepts Browse all of System Design Concepts

Software Architecture Design Patterns Microservices Caching Load Balancing Rate Limiting & Throttling Sharding & Replication Messaging & Event-Driven Architecture Domain-Driven Design Observability & Monitoring Serverless Architecture

Topics in Testing Browse all of Testing

Software Testing Unit Testing & TDD API Testing Performance Testing

Topics in Security Browse all of Security

Web Security & OWASP Top 10 Authentication & Authorization Cryptography & TLS

Topics in Database Technologies Browse all of Database Technologies

SQL Fundamentals Database Design

Cross-cutting topics 32 topics

Interviewers also test these - they're common to every stack, whichever one you picked above.

Topics in System Design Concepts Browse all of System Design Concepts

Software Architecture Design Patterns API Design Microservices Distributed Systems Fundamentals Caching Load Balancing Rate Limiting & Throttling Sharding & Replication Messaging & Event-Driven Architecture Domain-Driven Design Observability & Monitoring Serverless Architecture

Topics in Computer Science Fundamentals Browse all of Computer Science Fundamentals

Big-O & Complexity Analysis Arrays, Strings & Hash Tables Linked Lists, Stacks & Queues Trees, BSTs & Heaps Graphs Sorting, Searching & Recursion Operating Systems Concurrency & Multithreading Networking for Developers Git & Version Control

Topics in Testing Browse all of Testing

Software Testing Unit Testing & TDD API Testing Performance Testing

Topics in Security Browse all of Security

Web Security & OWASP Top 10 Authentication & Authorization Cryptography & TLS

Topics in Database Technologies Browse all of Database Technologies

SQL Fundamentals Database Design

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Likely follow-ups Would you return 403 or 404 when a caller asks for a record they are not allowed to see?404 avoids confirming the record exists, and 403 is clearer when the caller already knows about the resource. Name the leak you are avoiding. A user changes /orders/42 to /orders/43 and sees someone else's order. What check was missing?

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