Library

Python

Core language mechanics — the fundamentals worth actually understanding, not memorizing.

18 lessons · 74 cards

Data structures & algorithms

The patterns that show up over and over — arrays, hash maps, trees, and how to recognize which one fits.

17 lessons · 71 cards

OOP & design patterns

SOLID, composition over inheritance, and the patterns worth recognizing in real code.

17 lessons · 68 cards

Django

ORM internals, request lifecycle, and the parts of the framework worth understanding, not just using.

18 lessons · 75 cards

Databases & SQL

The actual language of relational data — queries, joins, and the practical skills behind working with SQL day to day, not just the system-design trade-offs.

16 lessons · 65 cards

Git & Version Control

The tool every other domain in this app assumes you already know — commits, branches, and the actual mental model behind them, not just a list of commands to memorize.

14 lessons · 57 cards

System design & architecture

Trade-offs at scale — caching, queues, consistency, and how real systems actually fail.

18 lessons · 71 cards

Cloud & Serverless Infrastructure

How real infrastructure scales: container deployments, serverless compute, queues and schedulers, presigned URLs, OIDC federation, and the entire class of gotchas that appear once you're managing real cloud resources.

17 lessons · 69 cards

Auth, Authorization & Multi-Tenancy

Who is this user, what can they do, and whose data should they see? Authentication (proving identity), authorization (granting permissions), and multi-tenancy (safe isolation between customers). Hashing passwords, managing sessions, issuing tokens, and the gotchas that leak data across tenants.

17 lessons · 72 cards

WhatsApp & Meta Platform Integrations

How to wire a real product into a third-party messaging platform, using Meta's WhatsApp Business Platform as the concrete, working example — Business Manager, Meta for Developers, access tokens, templates, webhooks, and the trade-offs behind each design decision.

19 lessons · 74 cards

Payments & Financial Systems

How real products safely move money: gateway integration, why the webhook is the source of truth (not the browser redirect), idempotency, and the double-entry ledger patterns behind every serious billing system.

11 lessons · 39 cards

AI Agents & LLM Integration

Building a real, production LLM-powered feature: tool-calling architecture, the propose-then-confirm pattern for anything that writes data, authorization that never trusts the model, and the genuine bugs this kind of system produces.

17 lessons · 66 cards