Module 8 
Contest guide
Contest guideHLD basics
SDE-2 loops at all six target companies include an HLD round, and the prompts repeat: notifications, subscriptions, feeds, booking, chat, tagging. Freshers get the lighter end.
- Lessons
- 9 · 2 h 32 min
- Problems
- 19
- Getting started
- Optional
- SDE-1
- Recommended
- SDE-2
- Core
- Plan
- Complete
Lessons
- 1The HLD answer order15 min
- 2Back-of-the-envelope numbers15 min
- 3Scaling a stateless service15 min
- 4Caching20 min
- 5Databases at scale20 min
- 6Queues and async work20 min
- 7Rate limiting and protecting the system15 min
- 8Unique IDs and the URL shortener20 min
- 9Consistency without the jargon soup12 min
Part of Oni. See plans →
Problems
- Not started URL shortener Board High-level design Difficulty 2 of 5 45 min Atlassian
- Not started Pastebin Board High-level design Difficulty 2 of 5 45 min
- Not started Distributed rate limiter Board High-level design Difficulty 3 of 5 45 min
- Not started Notification service Board High-level design Difficulty 3 of 5 60 min Zomato, Uber +2
- Not started Subscriptions on a payment gateway Board High-level design Difficulty 4 of 5 60 min Razorpay, PhonePe
- Not started Splitwise at scale High-level design Difficulty 3 of 5 45 min Uber
- Not started Cross-product tagging High-level design Difficulty 3 of 5 45 min Atlassian
- Not started Live order tracking Board High-level design Difficulty 3 of 5 60 min PhonePe
- Not started Ticket booking at flash-sale traffic Board High-level design Difficulty 4 of 5 60 min Razorpay, Atlassian
- Not started Photo feed Board High-level design Difficulty 4 of 5 60 min Atlassian, PhonePe +1
- Not started Group chat Board High-level design Difficulty 4 of 5 60 min Razorpay, Uber
- Not started Distributed job scheduler Board High-level design Difficulty 4 of 5 60 min Razorpay
- Not started Leaderboard High-level design Difficulty 3 of 5 45 min Goldman Sachs (India)
- Not started Food or services marketplace Board High-level design Difficulty 4 of 5 60 min Flipkart, Uber
- Not started Search autocomplete at scale Board High-level design Difficulty 3 of 5 45 min
- Not started Payment system Board High-level design Difficulty 4 of 5 60 min
- Not started Central authentication High-level design Difficulty 3 of 5 45 min Uber
- Not started Most engaged documents feed Board High-level design Difficulty 4 of 5 60 min Atlassian
- Not started HLD building blocks Quiz Difficulty 3 of 5 20 min