Free System Design Course  ·  20 Modules  ·  Beginner to Confident

Learn system design
from first principles.

We trace every byte from your keyboard to a server on the other side of the planet — and back. 20 interactive modules. Zero cost. Zero fluff. The knowledge you need to design and explain real software systems.

Start Module 01 — Free → Browse all modules
20
Modules
14h
Total content
Free
Always
Beginner track · 20 modules

Everything you need.
In order.

The course is one progressive story — each module builds on the last. Start at Module 01 and work forward. The order matters.

M.01
What is a System?
Parts, atoms, and one HTTP request traced end-to-end
42 minLab
→ M.02
Client–Server
The asker and the answerer — and why the asymmetry exists
38 minLab
→ M.03
HTTP & HTTPS
Methods, headers, status codes, TLS — the whole picture
44 minLab
→ M.04
REST APIs
How services talk to each other — and what "RESTful" actually means
40 minLab
→ M.05
SQL vs NoSQL
When to use a relational database and when not to
46 min
→ M.06
Indexes & B-Trees
Why queries are fast — and why they sometimes aren't
42 minLab
→ M.07
Caching
Cache-aside, write-through, TTL, invalidation — all the patterns
48 minLab
→ M.08
Latency & Throughput
Measuring what matters — and how they trade off against each other
36 min
→ M.09
Scaling
Vertical vs horizontal — when to scale up and when to scale out
44 min
→ M.10
Load Balancing
Round-robin, least-connections, consistent hashing — and why it matters
42 minLab
→ M.11
DNS
How a hostname becomes an IP — the full resolver walk
38 minLab
→ M.12
CDNs
Edge servers, PoPs, cache-control — serving users faster worldwide
40 min
→ M.13
Statelessness
Why stateless servers scale and stateful ones don't
36 min
→ M.14
Auth
Sessions, JWTs, OAuth — how identity works across requests
50 minLab
→ M.15
Logging & Metrics
Observability — knowing what your system is doing in production
38 min
→ M.16
Reliability
SLAs, SLOs, redundancy, failover — building things that don't break
46 min
→ M.17
Build: URL Shortener
Design a production URL shortener — end-to-end architecture walk
55 minBuild
→ M.18
Build: Image App
Storage, CDN, processing pipelines — designing an Instagram-like system
55 minBuild
→ M.19
Messaging & Queues
Kafka, RabbitMQ, async patterns — decoupling at scale
Coming soon
 M.20
Interview Toolkit
The framework, vocabulary, and templates for any system design interview
60 min
→
Start at Module 01 → 42 min · no sign-up needed
Why this course

Different by design.

◈

First principles, not patterns

We don't hand you a "design Twitter" template. We start with what a system actually is, and build from there. When you understand the primitives, every pattern becomes obvious.

⇌

Interactive where it counts

DNS resolution, TCP handshakes, cache hit/miss ratios — you step through simulations and watch the data move. Reading about it is not the same as seeing it.

▥

Zero fluff, zero paywall

No video intros. No 40-slide decks. No "premium tier." Every module is tight, dense, and free. We cut anything that isn't earning its place.

Start learning — it's free →