System Design
For Software Engineers
Spend 30 minutes a day. Train to think, answer, and decide at a Principal Engineer bar—without interaction, fluff, or wasted time.
Free daily scenarios.
CALIBRATED FOR ENGINEERING LEADERS AT
Why traditional prep breaks down
at the Senior+ level
Most resources explain how systems work. Principal-level evaluation probes how you think.
The role isn’t about finding the “right” answer—it’s about the quality of your tradeoffs under real constraints.
"Calibrate your thinking through progressive answer quality—from common failure patterns to Principal-level depth and judgment."
No “One Right Answer”
Move past polished diagrams. Learn to navigate ambiguity, articulate assumptions, and defend your engineering judgment when tradeoffs are unclear and stakes are real.
Production Reality
Go beyond happy-path designs. Reason about failure modes, scalability limits, reliability tradeoffs, and performance under real-world constraints.
"I'd use Kafka here for the messaging queue because it scales well and is standard."
"Given the strict ordering requirement but low throughput (100 TPS), Kafka adds unnecessary operational complexity. A simpler Postgres-backed job queue suffices for v1, minimizing maintenance overhead."
Observe. Compare. Calibrate.
Zero Fluff.
No typing, no performative gamification. Pure calibration against the Principal bar.
Context & Constraints
Every day, receive a realistic system scenario.
Bad vs. Good vs. Best
Don't guess. See exactly why a "Senior" answer fails the "Principal" bar. Internalize the gap in judgment.
Interviewer Rubric
Understand the strong signals and red flags.
Free Sample Scenarios
Experience the full interview simulation format. These are real scenarios at the Principal bar—not watered-down teasers.
Distributed Rate Limiter
Design a rate limiting system for 5M RPS with sub-5ms latency overhead.
Start scenarioMicroservices vs Monolith
Navigate the build vs. migrate decision with real constraints and team dynamics.
Start scenarioAPI Performance Crisis
Debug latency spikes in production with real metrics and time pressure.
Start scenarioInvest in your career.
Ideally suited for Backend Engineers with 8-20+ years of experience targeting Staff/Principal roles.
Monthly
Less than the cost of a failed interview prep book
- ✓ Daily Interview Scenarios
- ✓ Full Archive Access
- ✓ Bad/Good/Best Analysis
- ✓ Cancel Anytime
Annual
$15/mo • Save 2 months
- ✓ Everything in Monthly
- ✓ 2 Months Free
- ✓ Priority Feature Access
- ✓ Interview Prep Commitment
Potential ROI: A $50K+ salary increase from landing a Principal role.
7-day money-back guarantee. No questions asked.
Common Questions
Is this for New Grads or Junior Engineers?
**No.** This product explicitly assumes 8+ years of experience. We do not explain basic concepts. We focus on the nuanced tradeoffs expected at Staff/Principal levels in Big Tech.
Does this include coding puzzles?
No. We focus exclusively on System Design, Architecture, Tradeoffs, and Operational Reality (Reliability, Scaling, Failure Modes).
How does the daily format work?
Every day, we unlock one new calibration scenario. You read the context, form your own answer, and then reveal our "Bad vs. Good vs. Best" analysis to calibrate your thinking.