FermiReps: System Design

Practice the engineering estimates that come up in system-design interviews. FermiReps gives you focused drills in QPS, storage, bandwidth, and capacity so you can work on turning large numbers into useful estimates.

SHOW YOUR REASONING Work through a question in your own words. Break it into smaller parts, state your assumptions, track units, and use rough arithmetic to reach an estimate.

PRACTICE ENGINEERING QUANTITIES Convert daily traffic into requests per second. Estimate how much data a system stores or transfers. Work through capacity questions and compare the scale of your answer with the scenario.

GET FEEDBACK ON YOUR WORK Submit your reasoning for AI-generated grading and feedback. Review a reference answer and worked solution to compare approaches. The focus is estimation: sensible rounding and justified assumptions matter alongside units and arithmetic.

REVISIT YOUR ATTEMPTS Use your history to review previous answers, scores, and feedback. See topic scores as you complete exercises.

SET YOUR PRACTICE RHYTHM Choose your training cadence and active hours, pause scheduled training, or start another exercise when you are ready. Enable optional iPhone notifications for new assignments and reminders.

FermiReps focuses on estimation practice for system-design interviews. It does not provide a complete system-design course or coding-interview preparation.

An account and internet connection are required. Sign in with an email link or choose a password. Before using the practice features, you must consent to sharing submitted answers and exercise content with OpenAI for grading. AI feedback can contain errors.

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