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Open SystemDecoder on a larger screen to build systems, run simulations, and inject chaos.
Daily Challenge
SystemArena
5
Questions
Think Deep
1×
Daily Shot
5 sharp system design questions. One attempt daily — streaks, XP & leaderboard.
What's waiting for you on desktop
Live Simulations
Watch latency spike, queues fill, and nodes fail in real time. Every slider change is instant.
Visual Architecture Canvas
Drag nodes, draw edges, and build any distributed system topology from scratch.
Chaos Engineering
Kill servers, introduce packet loss, throttle CPUs — and watch your system react.
Real-time Insights
Throughput, p99 latency, error rates — all charted live as your simulation runs.
40+
Concepts
<1s
Feedback
∞
Replays
"The best way to understand a distributed system
is to break it."
Engineers don't memorise database names. They reason from workloads. This module trains that exact thinking.
Workload-first reasoning
Every choice starts from access patterns, not product names.
Tradeoffs, not answers
The same data can live in multiple systems for different reasons.
Engineering constraints
Scale, schema flexibility, and query patterns drive architecture.
Progressive branching
Each step reveals one layer of the decision tree — no overload.
How This Works
Each decision narrows the database universe. You'll traverse 3–4 layers of engineering tradeoffs before reaching concrete database families. Every ignored branch remains visible — architects understand the roads not taken.