Worked example: design an API rate limiter
One strong design for a junior-level question, from the first clarifying questions to what happens when the limiter itself breaks.
How practice works
Pick a question
Each question sets out the problem, its requirements, and what the grading looks at. Reading them is free, with no account needed.
Talk it through
Describe your design out loud and watch the diagram build as you speak. Type or edit the diagram directly whenever that is easier. There is a clock, but no deadline.
Read your feedback
Submit when you are ready. The grading goes through each criterion and says what your design covered and what it missed. Then compare it with one strong example design.
Different is not wrong
Grading checks concerns, not components. A design that differs from the example can still meet every criterion, and the feedback says how yours compares.
- Read scalingMet
- You used read replicas. The example puts a cache in front of the database instead. Both work: replicas avoid cache invalidation but can lag slightly behind writes.
- Hot keysMissed
- Your design does not say what happens when one link goes viral. The example serves popular redirects from a CDN.
Part of Lycana Pro
Grind uses your Lycana account and plan. There is no separate subscription.
See plans and prices on lycana.aiFree account
Practise on the same AI command and voice allowances as the rest of Lycana, with a few gradings each month.
Lycana Pro
Unlimited practice, subject to fair use. Practice does not use Pro's AI command or voice allowances.