System Design Diagrams

Visualize system designs with Mermaid for architecture reviews, technical interviews, and documentation. Use flowcharts for high-level architecture, sequence diagrams for data flows, and C4 diagrams for hierarchical decomposition. Text-based diagrams iterate faster than whiteboard drawings.

Why Use Mermaid

  • Interview prep — Practice system design with diagrams you can iterate on quickly
  • Architecture reviews — Present designs with clear visual hierarchy
  • RFC documentation — Include architecture diagrams in technical proposals
  • Scalability planning — Visualize read replicas, caches, queues, and sharding
  • Version control — Track architecture evolution through Git history

Example Diagram

flowchart TB
    subgraph Users
        WEB[Web Browser]
        APP[Mobile App]
    end

    subgraph CDN & Load Balancing
        CDN[CDN / Static Assets]
        LB[Load Balancer]
    end

    subgraph Application Tier
        API1[API Server 1]
        API2[API Server 2]
        API3[API Server 3]
    end

    subgraph Cache Layer
        REDIS[(Redis Cluster)]
        CDN_CACHE[Edge Cache]
    end

    subgraph Data Layer
        PRIMARY[(Primary DB)]
        REPLICA[(Read Replica)]
        SEARCH[(Search Index)]
        BLOB[Blob Storage]
    end

    subgraph Async Processing
        QUEUE[[Message Queue]]
        WORKER1[Worker 1]
        WORKER2[Worker 2]
    end

    WEB --> CDN --> LB
    APP --> LB
    LB --> API1 & API2 & API3

    API1 & API2 & API3 --> REDIS
    API1 & API2 & API3 --> PRIMARY
    PRIMARY --> REPLICA
    API1 & API2 & API3 --> SEARCH
    API1 & API2 & API3 --> BLOB

    API1 & API2 & API3 --> QUEUE
    QUEUE --> WORKER1 & WORKER2
    WORKER1 & WORKER2 --> PRIMARY

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Frequently Asked Questions

More Use Cases

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