CRED.

The rounds, as candidates describe them

1. Machine coding2 to 2.5 hours on HackerRank, extending a boilerplate codebase that ships with unit tests.source ↗
2. DSA and high-level designA short DSA interview plus a 45-minute HLD on entities, APIs and concurrency.source ↗
3. Design and LLD (onsite)Lead a design from scratch, then submit a design document and a working prototype within 24 hours.source ↗
4. Hiring managerPast projects, how you would scale parts of the product, and fundamentals.source ↗

• Design a flight booking system like MakeMyTripSystem design
  IP-19 · Design a Hotel Reservation System →SQ-11 · IRCTC Tatkal Ticket Booking System →reported in:LeetCode Discuss · CRED SDE-2 interview experience, Dec 2025 ↗
• Design a Ride-Hailing ServiceSystem design
  SQ-09 · Uber →IP-13 · Design a Proximity Service →reported in:LeetCode Discuss · CRED SDE-1 interview experience, InDrive-like platform (2025) ↗
• Design a payment-method recommendation systemLow-level design
  IP-20 · Design a Payment System →SQ-18 · Razorpay Payment Gateway →reported in:LeetCode Discuss · CRED SDE-II backend offer (2022) ↗LeetCode Discuss · CRED backend developer, payment aggregator machine coding (2024) ↗
• Design a microprocessor with registersLow-level design
  no lesson for this one yetreported in:LeetCode Discuss · CRED machine coding round (2024) ↗LeetCode Discuss · CRED machine coding round, backend engineer (2023) ↗
• Design a File Sync ServiceSystem design
  IP-10 · Design a File Sync Service (Dropbox / Google Drive) →SQ-08 · AWS S3 →reported in:LeetCode Discuss · CRED SDE-II backend offer, Google Drive design (2022) ↗
• Compute metrics over a time range from an event logLow-level design
  IP-15 · Design a Metrics Monitoring and Alerting System →W08 · DAY 03 · Data Modeling for Analytics →reported in:LeetCode Discuss · CRED SDE-1 interview experience (2025) ↗
• Design an in-memory databaseLow-level design
  IP-03 · Design a Distributed Key-Value Store →reported in:LeetCode Discuss · CRED backend engineer offer, Dec 2021 ↗
• Design a service that calls an endpoint at a fixed intervalLow-level design
  IP-17 · Design a Distributed Job Scheduler →W02 · DAY 05 · Distributed Cron & Job Scheduling →reported in:LeetCode Discuss · CRED backend engineer offer, Dec 2021 ↗

• Design an E-commerce Flash SaleSystem design
  W02 · BOSS · The Ultimate System Design Interview →W04 · DAY 03 · Thundering Herd →
• Design credit card bill payments with remindersSystem design
  IP-20 · Design a Payment System →W02 · DAY 02 · Idempotency in Practice →IP-06 · Design a Notification System →
• Design a rewards points ledgerSystem design
  W03 · DAY 05 · Audit Log System →W03 · DAY 02 · Transactional Outbox →
• Design a Notification SystemSystem design
  IP-06 · Design a Notification System →W06 · DAY 01 · Designing a Real-Time Notification Platform →

Study path

Every lesson the questions above point to, once, in order.

1. 01IP-19Design a Hotel Reservation System
2. 02SQ-11IRCTC Tatkal Ticket Booking System
3. 03SQ-09Uber
4. 04IP-13Design a Proximity Service
5. 05IP-20Design a Payment System
6. 06SQ-18Razorpay Payment Gateway
7. 07IP-10Design a File Sync Service (Dropbox / Google Drive)
8. 08SQ-08AWS S3
9. 09IP-15Design a Metrics Monitoring and Alerting System
10. 10W08 · DAY 03Data Modeling for Analytics
11. 11IP-03Design a Distributed Key-Value Store
12. 12IP-17Design a Distributed Job Scheduler
13. 13W02 · DAY 05Distributed Cron & Job Scheduling
14. 14W02 · BOSSThe Ultimate System Design Interview
15. 15W04 · DAY 03Thundering Herd
16. 16W02 · DAY 02Idempotency in Practice
17. 17IP-06Design a Notification System
18. 18W03 · DAY 05Audit Log System
19. 19W03 · DAY 02Transactional Outbox
20. 20W06 · DAY 01Designing a Real-Time Notification Platform