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Don't just learn how systems work. See them work.
Every concept is an animated, narrated visualisation you can play, pause and interrogate — requests flowing, partitions rebalancing, caches collapsing under load, architectures evolving decision by decision.
For backend engineers, system designers, and interview candidates — 100% free, no sign-in.
- visual modules
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- systems designed
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- AI modules
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- engineering domains
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Start with one of these.
Four picks across different areas of the catalogue — 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 6 parts.
Most explanations give you a single write-up per system. Every one of our 23 systems is structured into 5 parts — from the architecture to the interview pitch.
Watch the architecture become what it is.
Start from the simplest thing that works. Hit a real bottleneck. Weigh the options. Evolve — one decision at a time, animated.
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 exists to solve.
Visual Learning
The animated core: watch data move through the system, live.
Production
Configuration, capacity, monitoring, and the failure modes you will hit.
Insights
The non-obvious behaviour that only shows up under real load.
Interview Revision
Dense recall pass — the answers, the numbers, 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
168 modules across 8 engineering domains.
Every module is a subject broken into the parts that actually matter — pick one and go.
Common questions.
168 modules across 8 domains — Core Concepts, networking, databases, backend systems, system design, production engineering, architecture, and AI.
Pick one system you thought you understood.
Open it, watch it run, then break it. Pick any system — you're two clicks away from seeing it work.