Practice system design like it's the real interview.
PerfectSystemDesign runs a live, timed mock with an AI interviewer who probes your design, hints when you stall, and pushes back when you hand-wave — then scores you on the rubric senior interviewers actually use.
Every mock moves through six phases.
The same arc a real interviewer walks you through — paced by a timer so you learn to spend minutes where the signal is, not where it's comfortable.
A real interview loop, on demand.
Meet Mira, your AI interviewer
She asks the follow-ups a strong interviewer would. Stall and she nudges; hand-wave and she pushes back until you commit.
- ✓Adapts questions to your live design
- ✓Hints calibrated to your level
- ✓Never just hands you the answer
A whiteboard that speaks system design
Drop in clients, services, queues, and stores. Mira reads the board as you draw, so the conversation tracks what's actually on screen.
- ✓Components, arrows, and notes
- ✓Board state feeds the coaching
- ✓Replays back, step by step
Scored on the rubric that decides
Seven dimensions, a percentile against peers who took the same prompt, and an honest look at where your minutes actually went.
- ✓Per-dimension breakdown
- ✓Percentile vs. real peers
- ✓Time budget per phase
The prompts you'll actually be asked.
Forty-plus classics drawn from real senior loops, each with its own rubric and a deep-dive Mira won't let you skip. New prompts land every week.
One plan. Everything in it.
Run full mock interviews free, as many as you want. Unlock your scorecard when you're ready to see exactly how to pass.
PerfectSystemDesign Pro
- ✓Full rubric scorecard & peer percentile
- ✓Where you lost points + how to fix it
- ✓Unlimited in-session hints
- ✓Replay timeline + PDF export
- ✓40+ FAANG-style prompts, new ones weekly
The interview rewards reps. Start your first one now.
Twenty minutes from now you could have a real scorecard and a clear, named thing to fix. That's the whole game.