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Explore programming, software engineering, and systems. Find a topic, read a lesson, and practise what you learn.

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31 courses with lessons ready to read

Cloud engineering

Terraform for AWS Backends

Explore the available lessons in Terraform for AWS Backends. Read at your own pace and practice the concepts along the way.

7 lessons available

READ A LESSONStart Here: What Terraform Is
Event streaming

Kafka for .NET Developers 2026

Understand Kafka partitions, offsets, and delivery guarantees, then apply them to reliable .NET consumers.

10 lessons available

READ A LESSONCore Kafka Mental Model
Voice applications

Building Real-Time Voice Agents from Scratch

Explore how voice agents listen, respond, and handle interruptions, with attention to latency and audio flow.

8 lessons available

READ A LESSONPart I: Foundations
Secure systems

Authentication & Identity Fundamentals (2026)

Understand authentication, federation, sessions, and authorization through modern identity systems.

5 lessons available

READ A LESSONIdentity in 2026
Artificial intelligence

LLM as Judge: Reproducible Evaluation for LLM Systems

Explore how to evaluate LLM output, recognize judging biases, and combine model judgments with deterministic checks.

10 lessons available

READ A LESSONWhy Rigorous Eval Exists
Artificial intelligence

Agentic AI as a Part of Software Development

Explore agent workflows, context, evaluation, and the engineering practices needed to use AI in software development.

12 lessons available

READ A LESSONFoundations of Agentic AI
Software architecture

System Design Interviews for Software Developers with Examples

Practice reasoning about system design, explaining trade-offs, and working through realistic interview scenarios.

18 lessons available

READ A LESSONFoundations of System Design
Artificial intelligence

Surviving as a Developer When Most Code Is Generated by AI

Develop the review, debugging, and design skills needed to understand and maintain AI-assisted code.

23 lessons available

READ A LESSONUnderstanding the AI-Generated Code Reality
.NET development

Coding Gym Exercises with C#

Explore the available lessons in Coding Gym Exercises with C#. Read at your own pace and practice the concepts along the way.

8 lessons available

READ A LESSONFoundations: Core Data Structures
Secure systems

Web Security: The Modern Browser Model

Understand browser security boundaries, cross-origin requests, cookies, and the policies that protect web applications.

25 lessons available

READ A LESSONBrowser Security Foundations
Performance

Cache is King

Reason about cache placement, invalidation, consistency, and the failure modes behind apparently simple speedups.

16 lessons available

READ A LESSONCaching Fundamentals & Trade-offs
Live applications

Real-Time Web: Streaming, Events, and Live Systems

Compare polling, server-sent events, and WebSockets, then explore the design of reliable live applications.

3 lessons available

READ A LESSONServer-Sent Events (SSE)
Problem solving

Mastering Leet Code Algorithms

Recognize the patterns behind coding interview problems and practice explaining your solutions.

23 lessons available

READ A LESSONFoundation: Arrays & Strings
Developer tooling

Hermetic Builds

Understand reproducible builds, explicit inputs, and the hidden dependencies that make CI results unreliable.

18 lessons available

READ A LESSONFundamentals of Hermetic Builds
Runtime internals

Mastering Memory Management and Garbage Collection in .NET

Connect .NET garbage collection, allocation, ownership, and pooling to practical memory and performance decisions.

26 lessons available

READ A LESSONMemory Fundamentals
Troubleshooting

Debugging Under Pressure

Practice finding useful evidence, narrowing a fault, and choosing recovery actions during production incidents.

21 lessons available

READ A LESSONThe Moment of Crisis
Production systems

Production Observability: From Signals to Root Cause (2026)

Connect logs, metrics, and traces to questions about system behavior and the causes of production failures.

21 lessons available

READ A LESSONObservability Foundations
Artificial intelligence

2026 Modern AI Search & RAG Roadmap

Explore retrieval, search quality, grounded generation, and the evaluation of practical RAG systems.

38 lessons available

READ A LESSONFoundations of Modern AI Search
React data

Mastering Relay

Understand Relay's data model, fragments, mutations, and pagination when building GraphQL applications.

32 lessons available

READ A LESSONStop Thinking in Queries (Think in Fragments)
Cloud engineering

Mastering AWS

Explore AWS infrastructure, networking, security, reliability, and the trade-offs behind cloud architecture.

31 lessons available

READ A LESSONAWS Foundations & Core Services
.NET development

C# Programming

Build a deeper understanding of C# types, memory, asynchronous code, and modern language features.

36 lessons available

READ A LESSONC# Fundamentals & Type System
Application development

Java

Explore Java fundamentals, object-oriented design, collections, concurrency, and application development.

14 lessons available

READ A LESSONJava Fundamentals & Setup
Web interfaces

React

Build your understanding of React components, state, effects, and data flow through focused lessons.

22 lessons available

READ A LESSONPrerequisites & Fundamentals
Typed JavaScript

TypeScript

Learn to describe your data with TypeScript and use the type system to make JavaScript code clearer.

19 lessons available

READ A LESSONTypeScript Foundations
Programming

Python Programming

Write small Python programs while learning variables, collections, control flow, and functions.

18 lessons available

READ A LESSONPython Fundamentals
Application development

ASP.NET with .NET 10

Explore ASP.NET Core APIs, request handling, data access, testing, and deployment with .NET 10.

17 lessons available

READ A LESSONASP.NET Core & Minimal APIs Foundations
Functional programming

Functional Programming with F#

Use immutable data, functions, and F# types to model problems and build maintainable software.

18 lessons available

READ A LESSONImmutability & Expressions
Web interfaces

React Hooks

Build your understanding of React through focused lessons and examples.

4 lessons available

READ A LESSONLesson 1: Introduction to React Hooks
Databases

SQL Fundamentals β€” Query Any Database

Learn to ask questions of your data with SQL queries.

8 lessons available

READ A LESSONLesson 1: SELECT Basics β€” Asking Questions
Version control

Git Mastery β€” Version Control Without Fear

Get comfortable with version control, one Git concept at a time.

8 lessons available

READ A LESSONLesson 1: The Git Mental Model β€” Snapshots, Not Diffs
Application development

.NET developer interviews

Work through .NET development concepts and practise explaining how they work.

3 lessons available

READ A LESSONLesson 1: Async/Await and Task Parallel Library (TPL) Fundamentals
01 / UNDERSTAND

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02 / RECALL

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03 / RETURN

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Revisit practice questions over time as your review schedule develops.