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Design scalable systems.
Watch them fail under load.

PRISM is an interactive system design simulator. Build distributed systems on a canvas, fire real traffic, and see bottlenecks, cascading failures, and latency spikes — before interviewers do.

Run a Simulation Watch Demo

No credit card. No setup. Runs in your browser.

prism — system design simulator LIVE
WHAT PRISM DETECTS

Systems don't fail in theory.
They fail under load.

PRISM simulates real consequences. Every design decision has a cost — PRISM shows you exactly what it is.

Single Point of Failure

No redundancy. One node goes down, the whole system does.

100% downtime risk

Database Saturation

Write throughput exceeded. Queries queue faster than they drain.

P99 > 2,000ms

Queue Overload

Consumers can't keep up. Backpressure cascades upstream.

Depth: unbounded

Latency Spike

One slow dependency drags down your entire response time distribution.

Tail latency +800ms

Replica Lag

Primary/replica gap grows under write load. Reads return stale data.

Lag: 4.2s behind

Throughput Collapse

Circuit breaker trips. Requests rejected at the edge. System unavailable.

0 rps accepted
THE PROCESS

From blank canvas
to a scored system design.

01

Build your system

Drag real components — load balancers, caches, databases, queues — onto a blank canvas. No templates. No hand-holding. Just you and the system.

02

Simulate traffic

Fire live traffic at your design. Watch latency climb, queues saturate, and bottlenecks emerge in real time — before you defend your design in the room.

03

Get your score

Defend tradeoffs, answer component MCQs, receive a rubric-based evaluation scoring exactly how a senior interviewer would — across 5 engineering dimensions.

Take a full evaluation → Explore guided system designs
ENGINEERING REASONING

Tradeoffs matter.
PRISM shows why.

Every design decision has a consequence at scale. PRISM doesn't just score your system — it shows which decisions hurt you and exactly what they cost.

  • Scalability vs. simplicity
  • Consistency vs. availability
  • Latency vs. throughput
  • Cost vs. reliability
  • Sync vs. async processing
See your tradeoff score →
Tradeoff Analysis AI Evaluation
Decision under review
"You chose synchronous DB writes without a write-through cache."
Consequence at 50k RPS
Write latency
1,240ms
DB queue depth
12,400
Error rate
4.2%
Consider async writes via write-behind cache to decouple DB pressure.
THE PRISM FRAMEWORK

How senior engineers
evaluate system design.

PRISM scores your design across 5 dimensions — the same rubric used in real FAANG interview loops.

P
Problem UnderstandingDid you clarify scope, scale, and constraints before drawing anything?
R
Requirement AnalysisDid you capture functional and non-functional requirements?
I
Identification of ComponentsDid you identify the right services, boundaries, and data flows?
S
System DesignIs the design coherent, scalable, and resilient under realistic load?
M
Mitigations & TradeoffsCan you defend your decisions and reason through alternatives?
Engineers from these companies train with PRISM
START NOW

Your system is only as strong
as its weakest node.

Find it. Fix it. Think in systems.

Run your first simulation Take the full evaluation

Free to start. 5 simulations/month on the free plan.