Free Courses

Learn the most in-demand tech skills with animated diagrams and hands-on practice. Start from zero, go to job-ready — free, no signup, progress saved in your browser.

Python
Beginner → Advanced
1/10 chapters

Python Mastery: Zero to Production

See how Python really thinks — memory, loops and async, animated.

Start from your first line of code and finish writing fast, clean, production-ready Python. Every idea comes with a moving diagram, so you see what the code is doing.

Variables & memoryData structuresFunctions & closuresGeneratorsAsyncioReal scripts
Course outline
  1. Your first program & how Python runs it
  2. Variables, references & mutability (animated memory boxes)
  3. Lists, dicts, sets & tuples visualised
  4. Loops & comprehensions on a conveyor belt
  5. Functions, scope & the call stack
  6. Errors & debugging like a pro
  7. Generators & iterators: streaming big data
  8. Asyncio & the event loop race track
  9. Files, APIs & automation scripts
  10. Packaging, testing & shipping to production
Practice with: JSON Viewer, Regex TesterStart Chapter 1 →
AI
Beginner → Advanced
0/10 chapters

Generative AI & LLM Engineering

Tokens, embeddings, RAG and agents — explained with playable visuals.

The most hired-for skill today. Learn how large language models actually work and how to build real AI features: search over your documents, structured answers and tool-using agents.

Tokens & context windowsEmbeddingsVector searchRAGPrompt engineeringAgents & tool calling
Course outline
  1. What an LLM is (no maths needed)
  2. Tokens: watch text split into pieces
  3. Temperature, sampling & context windows
  4. Embeddings: meaning as points on a map
  5. Vector databases & similarity search
  6. RAG: the complete pipeline step by step
  7. Prompt engineering & structured JSON output
  8. Reducing hallucinations & evaluating answers
  9. Tool calling & AI agents
  10. Cost, latency & shipping AI to production
Practice with: Prompt Diff, JSON ViewerChapter 1 coming soon
Data
Beginner → Advanced
0/10 chapters

Data Analytics & Business Intelligence

From messy spreadsheets to dashboards and SQL insights.

Learn the full analyst workflow: clean data, query it with SQL, find patterns with statistics and present it with the right chart — all hands-on in your browser.

SpreadsheetsSQLJOINsData cleaningStatisticsCharts & dashboards
Course outline
  1. Thinking like an analyst
  2. Spreadsheet essentials & formulas
  3. Cleaning data: duplicates, blanks & types
  4. SQL basics: SELECT, WHERE, ORDER BY
  5. GROUP BY & aggregations, animated
  6. JOINs visualised row by row
  7. Statistics: mean, median, spread & percentiles
  8. Choosing the right chart
  9. Building a KPI dashboard
  10. Telling a story with data
Practice with: XLSX Studio, SQL PlaygroundChapter 1 coming soon
Systems
Intermediate
0/10 chapters

Modern System Design & API Architecture

Watch requests travel through caches, load balancers and queues.

Crack system design interviews and build systems that scale. Every concept is a live packet-flow animation instead of a static box diagram.

HTTP & RESTCaching & CDNsLoad balancingAuth (JWT, cookies)QueuesScaling databases
Course outline
  1. How a request travels the internet
  2. HTTP, REST & GraphQL compared
  3. Caching & CDNs: cache hit vs miss
  4. Load balancers & their algorithms
  5. Authentication: sessions vs JWT
  6. WebSockets vs SSE vs polling
  7. Message queues & async work
  8. Database scaling: replicas & sharding
  9. Rate limiting & reliability
  10. Designing real systems: URL shortener to chat app
Practice with: HTTP Request Builder, HAR AnalyzerChapter 1 coming soon
DevOps
Intermediate
0/8 chapters

Cloud, Containers & DevOps

Docker, CI/CD and Kubernetes made visual.

Learn how modern apps are packaged, tested and deployed. See containers, pipelines and clusters come alive step by step.

Linux & terminalGit workflowsDockerCI/CDKubernetesCloud basics
Course outline
  1. Terminal & Linux essentials
  2. Git branching, merging & rebasing animated
  3. What a container really is
  4. Writing Dockerfiles
  5. CI/CD pipelines visualised
  6. Kubernetes pods, services & scaling
  7. Cloud building blocks
  8. Monitoring, logs & incidents
Practice with: YAML toolsChapter 1 coming soon
Web
Beginner → Advanced
0/8 chapters

Modern Full-Stack & React Internals

How React renders, updates and talks to the server.

Go beyond tutorials: see the virtual DOM, re-renders, state and server rendering happen in front of you, then build a complete full-stack app.

HTML/CSS/JSTypeScriptReact renderingState managementServer renderingAPIs
Course outline
  1. How the browser draws a page
  2. Modern JavaScript & TypeScript
  3. React components & props
  4. State, effects & re-renders visualised
  5. Reconciliation & the virtual DOM
  6. Data fetching & caching
  7. Server rendering & hydration
  8. Building and deploying a full-stack app
Practice with: JS/TS Playground, HTML Live PreviewChapter 1 coming soon
AI
Beginner → Advanced
0/8 chapters

Machine Learning Foundations

Regression, trees and neural networks you can poke and tweak.

Understand how machines learn from data with sliders and live charts — gradient descent, overfitting and neural networks without heavy maths.

Data & featuresRegressionClassificationOverfittingNeural networksModel evaluation
Course outline
  1. What 'learning' means for a machine
  2. Features, labels & datasets
  3. Linear regression & gradient descent animated
  4. Classification & decision trees
  5. Overfitting vs underfitting
  6. Neural networks layer by layer
  7. Evaluating models: accuracy, precision & recall
  8. From notebook to real app
Practice with: CSV ViewerChapter 1 coming soon
Systems
Beginner → Advanced
0/8 chapters

Cybersecurity Essentials for Developers

See attacks happen — then learn to stop them.

Learn the security skills every developer needs: how hackers break apps, and how encryption, hashing and safe code keep users protected.

Hashing & encryptionHTTPS/TLSOWASP Top 10XSS & SQL injectionAuth securitySecure coding
Course outline
  1. How attackers think
  2. Hashing vs encryption
  3. HTTPS & TLS handshake animated
  4. SQL injection & how to block it
  5. XSS, CSRF & safe browsers
  6. Passwords, tokens & secure login
  7. Secrets & dependency safety
  8. Security checklist for shipping
Practice with: Hash GeneratorChapter 1 coming soon