From writing code to
thinking like an engineer.
Interactive challenges that take you from variables and loops all the way to Gang of Four patterns, distributed systems, and security CTFs — in TypeScript, Python, Java, Swift, or Go. No videos. No passive reading. Just code.
TypeScriptJavaScriptPythonJavaSwiftGo
Real code editor
Monaco editor (VS Code engine) in your browser. Syntax highlighting, autocomplete, error squiggles.
Instant feedback
Your code runs in a sandboxed environment. Results in under a second. No install required.
Beginner to architect
One continuous path — no jumping between platforms. Master every layer of the stack.
The full curriculum
Every module builds on the last. No gaps.
⚡
Module 0Free
Absolute Basics
Variables, loops, conditionals, functions. Start here.
12 challenges
🧱Module 1Free
Intermediate Building Blocks
Closures, classes, async/await, collections.
10 challenges
🏗Module 2Pro
SOLID Principles
The rules that separate code that scales from code that collapses.
10 challenges
🏭Module 3Pro
Creational Patterns
Factory, Builder, Singleton, Prototype — control how objects are born.
5 challenges
🔩Module 4Pro
Structural Patterns
Adapter, Decorator, Proxy, Composite — organize object relationships.
7 challenges
🧠Module 5Pro
Behavioral Patterns
Observer, Strategy, Command, State — define how objects communicate.
11 challenges
🏛Module 6Pro
Architectural Patterns
CQRS, Event Sourcing, Hexagonal — design systems, not just classes.
6 challenges
🌐Module 7Pro
Real-World Systems
Token buckets, LRU caches, connection managers under real constraints.
5 challenges
⏱️Module 8Pro
Concurrency & Async
Worker pools, async mutexes, debounce/throttle, and cancellation tokens.
9 challenges
🛰️Module 9Pro
Distributed Systems
Circuit breakers, sagas, outbox pattern, and 2-phase commit coordinators.
9 challenges
💾Module 10Pro
Data & Performance
LFU cache, B-Trees, Bloom filters, LSM-Trees, and singleflight deduplication.
10 challenges
🔒Module 11Pro
Security Engineering
Idempotency keys, HMAC signing, RBAC evaluation, and timing attack defense.
9 challenges
🚩CTF TrackCTF
Break & Patch
Exploit real vulnerabilities (SQLi, prototype pollution, SSRF) then patch the code.
10 challenges
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