Become a computer scientist, one runnable lesson at a time.
Python and JavaScript, frontend to backend, language basics to advanced DSA and System Design. Read a chapter, then run the code right here in your browser. No setup, no excuses.
Choose your track
From your first `print` to designing distributed systems.
Python
From print to FastAPI
Learn Python from absolute zero — variables, control flow, functions, classes — through async I/O and a production-grade backend with FastAPI.
JavaScript
Browser to backend, in one language
JavaScript and TypeScript: from variables to React, Next.js, and a Node + Express backend. The full stack in one track.
Data Structures & Algorithms
Big-O to graphs, trees, DP
The interview-essential DSA curriculum: Big-O, arrays, hash maps, linked lists, trees, graphs, dynamic programming, and advanced structures.
System Design
Scale, latency, durability
Real-world distributed systems: scaling, caching, databases, queues, and end-to-end case studies (Twitter feed, URL shortener).
Operating Systems
Processes, memory, files, I/O
What actually happens when you run a program. Processes, threads, scheduling, virtual memory, file systems, and the system call boundary.
Computer Networks
TCP/IP, HTTP, DNS, sockets
How a packet travels from your laptop to a server across the planet — IP, routing, TCP vs UDP, HTTP, TLS, and the socket API every framework wraps.
Git & Command Line
The toolbox every dev uses
The terminal, pipes, file permissions, find/grep — and the Git workflow you'll use every single day: branches, merging, push/pull, undoing mistakes.
Databases
SQL, joins, indexes, transactions
From SELECT to ACID. Schema design and normalization, joins, indexes, transactions and isolation levels, and when (and when NOT) to reach for NoSQL.
What's inside
Bite-sized lessons that build mental models, not just syntax. Code is explained line-by-line.
Every code block has a Try button. Python runs via Pyodide; JavaScript runs in a sandboxed iframe.
Curated DSA problems with starter code, hints, and full solutions. Submit & see your output instantly.
Project tracks with step-by-step plans — from a Todo CLI to a realtime chat to a mini search engine.
System design from CAP to caching to a Twitter-feed case study, written like a senior would explain it.
Quizzes inside lessons so you don't fool yourself about what you've actually learned.
Stop watching tutorials. Start typing.
Pick the first lesson, run the first snippet, and let the dopamine of ✓ correct drive the rest.
Start with "Hello, Python"