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Chapter tutorials — the same lesson sequence as Courses. Worked programs (a file, the output, then why) live under Programs.
Free chapter lessons. Same material as Courses.
Programming Languages
javascript
9 tutorials
Learn javascript programming
html
16 tutorials
Learn html programming
python
20 tutorials
Learn python programming
react
7 tutorials
Learn react programming
css
7 tutorials
Learn css programming
system-design
22 tutorials
Learn system-design programming
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Tutorial Index by Category
Use this index to jump directly to a specific lesson. This creates a complete path from hub pages to deep tutorials and helps you navigate chapter-by-chapter without relying on search.
react
javascript
css
python
- Day 1: Introduction to Python
- Day 10: Functions
- Day 11: Classes and Objects
- Day 12: Inheritance and Polymorphism
- Day 13: Modules and Packages
- Day 14: File Handling
- Day 15: Exception Handling
- Day 16: Advanced Data Structures
- Day 17: Basic Algorithms
- Day 2: Variables and Data Types
- Day 21: Web Development Basics
- Day 22: Working with APIs
- Day 23: Database Operations
- Day 3: Operators and Expressions
- Day 4: Strings and String Methods
- Day 5: Lists and List Methods
- Day 6: Tuples and Sets
- Day 7: Dictionaries
- Day 8: Conditional Statements
- Day 9: Loops and Iteration
html
system-design
- Lesson 1: When One Server Isn't Enough
- Lesson 10: Virtual Nodes and CDN Routing
- Lesson 11: The Simplest Database Interviewers Love
- Lesson 12: Replicating and Sharding a KV Store
- Lesson 13: Counting Without Collisions
- Lesson 14: Snowflake IDs at Scale
- Lesson 15: How Web Crawlers Actually Work
- Lesson 16: Crawling Billions of Pages
- Lesson 17: When Your App Needs to Ping Users
- Lesson 18: Ten Million Push Notifications
- Lesson 19: Why Your Feed Feels Instant
- Lesson 2: Scaling the Data Layer
- Lesson 20: Scaling Feeds Past the Celebrity Problem
- Lesson 21: How WhatsApp-Style Chat Works
- Lesson 22: A Hundred Million Messages a Day
- Lesson 3: Do the Math on a Napkin
- Lesson 4: What Interviewers Want in 45 Minutes
- Lesson 5: Token Bucket vs Sliding Window
- Lesson 6: Building a Distributed Rate Limiter
- Lesson 7: How Short Links Actually Work
- Lesson 8: Scaling Short Links to Millions
- Lesson 9: When Hash Modulo Breaks
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