Design Tinder: A System Design Interview Breakdown

Be able to design a Tinder-like swipe-matching platform end-to-end in an interview setting: define functional/non-functional requirements and APIs, guarantee consistent real-time match detection under concurrent swipes, generate low-latency personalized feeds at scale, avoid re-showing swiped profiles efficiently, and justify every architectural trade-off (Redis vs Cassandra LWT, pre-computed vs real-time feeds, Bloom filters) the way a senior or staff engineer would.

6 sections ยท 13 lessons

Course outline

Framing the Problem

  1. Functional and Non-Functional Requirements
  2. Core Entities and API Design

High-Level Architecture

  1. Profile Creation and Feed Generation Flow
  2. The Swipe and Matching System

Consistent, Low-Latency Swipe Matching

  1. Why Race Conditions Threaten Match Detection
  2. Cassandra LWT and Compound Partition Keys
  3. Redis and Lua Scripts as the Preferred Solution

Low-Latency Feed Generation

  1. Why Naive SQL and Pure Real-Time Search Both Fail
  2. The Hybrid Approach: Cache with Elasticsearch Fallback

Avoiding Re-Shown Profiles

  1. From Database Queries to Client-Side Caching
  2. Bloom Filters for Space-Efficient Swipe History

Scale, Trade-offs, and Final Architecture

  1. Scale Metrics and Why They Drive Every Component Choice
  2. The Five Key Trade-offs and Final Component List

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