Don't just learn how systems work. See them work.
An engineer's journey has no last page.
From your first HTTP request to designing Uber to shipping AI agents. Each module pairs a written explanation with an animated, narrated visualization you can play, pause and replay.
For backend engineers, system designers, and interview candidates — 100% free, no sign-in required.
- visual modules
- 176
- systems designed
- 31
- AI modules
- 75
- engineering domains
- 8
- Core ConceptsDS · OS · HTTP · 33 modulesday 1
- NetworkingTCP · DNS · TLS · 7 modules
- Databasesindexes · MVCC · 4 modulesfirst job
- Backend SystemsKafka · Redis · 6 modules
- System Designreal systems · 31 modulesowning a service
- Architecturesagas · CQRS · 14 modules
- Production Eng.failures · SRE · 6 moduleson-call at 3am
- Modern AILLMs · RAG · agents · 75 modulesnew tech every year
One request. A whole system behind it.
Watch a request travel through a load balancer, service, cache, and database. See what changes when the cache misses, traffic spikes, and the system recovers.
Start with one of these.
Four picks across different areas of the catalog — no particular order, just a good place to begin.
Backend Systems
Kafka
Watch producers, partitions, and consumer groups move a message end to end.
Open itNetworking
HTTP
The request/response cycle every backend system is built on.
Open itSystem Design
Design Uber
Follow a real system from requirements to a scaled, evolved architecture.
Open itProduction Engineering
Cache Stampede
See a real production failure form, cascade, and recover.
Open itOne system, broken into 5 parts.
Each of the 31 systems is taught in the same 5 lessons, from the complete design and its animated design journey to the interview pitch.
The full design, with the architecture evolving on screen.
Requirements, components, data paths and scaling decisions, explained end to end. The embedded Visual Design Journey starts from the simplest version that works and evolves it one bottleneck and one decision at a time.
Want to know how a system works? Break it.
You do not really understand a system until you have watched it fail. Each scenario runs the full arc — the trigger, the amplification, the collapse, and the mitigation that brings it back.
Simulation · Cache stampede
You already use these. Now look inside them.
Kafka, Redis, RabbitMQ, PostgreSQL, MongoDB, Cassandra and more — each of the 10 technologies broken into 4 parts, from first principles to interview recall.
Live visualization · Kafka
Producers write, partitions fill, consumer groups rebalance, replication keeps the log durable — watch each mechanism instead of reading about it.
Fundamentals
The mental model: what the system is and what problem it solves, with the animated Visual Learning walkthrough of data moving through it.
Production Engineering
Configuration, capacity, monitoring, and the failure modes you will hit.
Engineering Insights
Design decisions, trade-offs, comparisons and common mistakes.
Interview & Revision
A dense recall pass: the questions, the numbers and the trade-offs.
Don't just learn what AI is. See what happens inside it.
75 modules across 8 tracks — from a single token being predicted, through retrieval pipelines and agent loops, to the infrastructure that serves them in production.
Live visualization · AI pipeline flow
Simple to watch. Serious to build.
Lessons start from the questions engineers actually ask and draw on official documentation and specifications. Each visual journey is modelled as a working system before anything is animated, and lessons are revisited and corrected when something is wrong.
- Problem first
- A mechanism appears only after you’ve seen why it’s needed.
- State-driven journeys
- What changes on screen corresponds to a change in the modelled system.
- Corrected and dated
- Lesson pages show when their content last meaningfully changed.
176 modules across 8 engineering domains.
Each domain shows how many modules and lessons it contains. Pick one to see everything in it.
Common questions.
176 modules across 8 domains: AI, Core Concepts, System Design, Architecture, Networking, Backend Systems, Production Engineering, Databases.
The map keeps growing. So will you.
Pick one system you thought you understood. Open it, watch it run, then break it. Free to learn without an account; sign in only if you want to save your progress.