Advanced~6h
Case Studies in System DesignInterview Readiness Check
Real-world system design walkthroughs: URL shortener, Twitter, WhatsApp, Instagram, and more.
url-shortenertwitterwhatsappinstagramyoutubedropboxrazorpayswiggycase-study
Learning path
Try a sample question
You're designing a URL shortener (like bit.ly). A user submits a long URL and gets a short code like 'abc123'. What is the minimum data you need to store?
A.The full URL only — derive the short code from a hash
B.Both the long URL and a pre-generated list of short codes
C.short_code → long_url mapping with created_at and optional expiry
D.User account details, long URL, and analytics per click
Sign up free to take the full check and see the answer with an explanation.
What this module tests
- Conceptual understanding of case studies fundamentals
- Trade-offs and design decisions in real system scenarios
- url-shortener and twitter — applied knowledge
- Interview-style reasoning and explanation quality
Free to start
Take the Case Studies check →
10 questions · Dimension scoring · AI coach feedback · Shareable result
Test your knowledge — free →No credit card · Takes 10–15 min
Frequently asked questions
- What does the Case Studies check test?
- The check covers real-world system design walkthroughs: url shortener, twitter, whatsapp, instagram, and more. Questions span beginner to advanced difficulty and test both conceptual understanding and practical trade-off reasoning.
- What keywords should I know for Case Studies?
- Key concepts include: url-shortener, twitter, whatsapp, instagram, youtube, dropbox, razorpay, swiggy, case-study. These frequently appear in system design interviews at product and infrastructure companies.
- How many questions are in the check?
- Each check has 10 questions — a mix of MCQ and short-answer. You get scored by dimension (e.g., scalability, consistency) so you know exactly where to focus.
- How long does it take to study Case Studies?
- Most engineers spend around 6 hours on this module. The check itself takes about 10–15 minutes. You can retake it up to 3 times per day.
- What prerequisite knowledge do I need before Case Studies?
- Case Studies builds on Scalability and Reliability and Distributed Systems. Complete those first for the best results.
- Is url-shortener, twitter, whatsapp covered?
- Yes. The Case Studies module covers url-shortener, twitter, whatsapp among other key concepts. The check includes questions that reflect real system design interview patterns.