SystemDecoder
Interactive system design

Understand how systems behave —
by simulating them

Interactive system design with real-time insights. No static diagrams — real behavior.

Free to start · No credit card required

📐

System design is abstract

Boxes and arrows hide what actually happens under load.

See real behavior, not diagrams

Watch latency spike, queues fill, and failures cascade in real time.

🧠

Build intuition faster

Change a slider. See the outcome. Understand the trade-off instantly.

Live system metrics

82ms

Latency

1.2k/s

Throughput

0.3%

Error Rate

43

Queue

218ms

p99

99.97%

Uptime

82ms

Latency

1.2k/s

Throughput

0.3%

Error Rate

43

Queue

218ms

p99

99.97%

Uptime

40+

Interactive concepts

<1s

Feedback loop

3

Complexity tiers

Replays

Interactive Learning

Learn with interactive simulations

⚖️

Round Robin

Load Balancing

Watch requests distribute evenly across servers. See what happens when one goes down.

🌊

Backpressure

Flow Control

Producer floods the queue. Adjust consumer rate and recovery strategy live.

🔄

HTTP Polling

Communication

See wasted round-trips in real time. Compare against WebSocket efficiency.

🔑

Rate Limiting

Token Bucket

Configure burst capacity. Watch tokens replenish and requests get dropped.

Full simulator on desktop

Build architecture graphs, run simulations, and inject chaos on a larger screen.