AI can write code faster than any human. But it cannot decide what to build.
The engineers who thrive in the AI era are the ones who understand the architectural
patterns behind every system. This framework gives you that understanding.
AI writes code, you design systems
AI tools generate implementation. You provide the architecture. Knowing which building blocks to compose and why is the skill that matters most.
Same patterns everywhere
Instagram, Netflix, Uber, Slack, Stripe. Different products, same 7 building blocks. Learn the pattern once, apply it to any system.
Free and open source
The framework is free. Read the articles, try the challenges, use it in your work and interviews. No account required.
The 7 Building Blocks
Every software system is composed from these 7 universal building blocks.
Two handle tasks, five handle storage. Together they can model any system.
Task
Service
Receives a request, does work, sends a response. The backbone of every API.
Task
Worker
Picks up tasks from a queue and processes them in the background, at its own pace.
Storage
Key-Value Store
Lightning-fast lookups by key. Caching, sessions, feature flags.
Storage
File Store
Stores large blobs: images, videos, PDFs. Optimized for size, not queries.
Storage
Queue
Decouples producers from consumers. Makes systems resilient to spikes and failures.
Storage
Relational Database
Structured data with relationships. Transactions, constraints, complex queries.
Storage
Vector Database
Similarity search for AI. Find content by meaning, not exact match.
Task blocks (do work) Storage blocks (hold data)
Prefer to Watch? The Full Video Series
The same framework as a free 7-lesson lecture series — the original recordings that started it all. Read the articles, watch the videos, or both.
You can't read your way to judgment — you have to build. Design Instagram, Netflix, and Uber
from the blocks up. Each challenge hands you real requirements and asks you to pick the right
blocks and compose them into a working system.
You can name all 7 building blocks and the 3 forces that act on them. That's the vocabulary — and it's further than most engineers ever get. But it isn't judgment yet. Knowing what a queue is won't tell you whether this system needs one, or what breaks when traffic spikes at 3am.
That instinct forms two ways: by studying how real systems were solved, and by designing your own under real constraints and getting told where your reasoning held and where it didn't. That's what the courses are — not more to read, but reps that turn what you just learned into judgment you own.
What you just did — free
The knowledge
Read the 7 framework articles
Watch the full video series
Play the building blocks game
Try Design with Blocks on your own app
What builds judgment — the courses
The reps that make it stick
12 structured lessons with speaker notes
2 hands-on Python discovery labs
3-part system design challenge with AI feedback
Comprehensive assessment + real-world case study
Lifetime access to everything
Want a mentor on your own code — free?
Scaffold (beta) coaches you through real tasks in your repo and reports your growth on every commit — the fastest way to start building judgment on code you already care about. Try Scaffold →
Continuing Lecturer at UC Berkeley School of Information. Software engineer and engineering manager with 15+ years building systems at leading technology companies, including AncestryDNA and Morgan Stanley. Teaching engineers to think in systems.
