Design a meeting scheduler and shopping cart
Company: Uber
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Technical Screen
You are asked to do two system-design prompts.
# Prompt A: Meeting Scheduler
Design a meeting scheduling system (similar to a calendar + scheduling assistant) that allows users to:
- Create meetings with a set of attendees.
- Find available time slots for all attendees within a time range.
- Send invitations and track RSVP status (accepted/declined/tentative).
- Prevent double-booking (or clearly define how conflicts are handled).
Discuss:
- Core APIs.
- Data model and storage choices.
- How you compute availability efficiently.
- Consistency requirements and concurrency control.
- Indexing strategy and performance at scale.
Assume:
- Millions of users, each with many events.
- Time zones matter.
# Prompt B: Online Shopping Cart (Multi-merchant)
Design an online shopping cart service where:
- A user can add/update/remove items in their cart.
- The platform is a marketplace: **each merchant has a separate cart per user** (i.e., user has one cart per merchant).
- You must handle frequent cart updates and decide how to index and store carts.
Discuss:
- Core APIs.
- DB schema (or document model) and indexing.
- How to handle concurrency (multiple devices/tabs).
- How pricing/promotions/inventory are handled (cart vs checkout).
- Caching strategy and data retention (TTL) for abandoned carts.
- Failure modes and consistency trade-offs.
Quick Answer: This question evaluates system design skills across distributed systems, API design, data modeling, indexing, caching, concurrency control, consistency trade-offs and scalability, applied to a meeting scheduler and a multi-merchant shopping cart.