Flipkart / Shopping site — Detailed

flowchart TB
  subgraph Clients
    WEB
    MOB
  end

  subgraph Edge
    CDN
    GW[GraphQL Gateway]
  end

  subgraph Catalog
    PSVC[Product Service]
    PDB[(Products)]
    SELLER[Seller Hub]
    PRICE[Price / Offer engine]
  end

  subgraph Browse
    SRCH[Search]
    INVIDX[(Inverted index)]
    REC([Recommendations])
    HOME[Home page assembly]
  end

  subgraph Buy[Buy flow]
    CART[Cart]
    CKT[Checkout]
    PROMO[Coupons / Plus benefits]
    EMI[EMI / financing]
    UPI[UPI / Cards / Wallet]
    PAY[Payment Service]
    PG[Payment Gateways]
  end

  subgraph Order
    OSVC[Order Service]
    SAGA([Saga orchestrator])
    INV[Inventory]
    INVDB[(Inventory)]
  end

  subgraph Logistics[Ekart-style logistics]
    OMS[OMS]
    SHIP[Shipment]
    HUB[Hubs / sorting]
    LASTM[Last mile]
    TRK[Tracking]
  end

  subgraph Sale[Big Billion Day]
    LANE[[Sale lane / VIP queue]]
    PRE[Pre-warm caches]
    THROT[Order rate throttle]
    RES[Soft reservations TTL]
  end

  subgraph After
    RET[Returns / replacement]
    REF[Refund]
    SUP[Support / chatbot]
  end

  Clients --> CDN --> GW
  GW --> Catalog
  GW --> Browse
  GW --> Buy
  Buy --> Order
  Order --> Logistics
  Order --> After
  Sale --- Order

    classDef client fill:#dbeafe,stroke:#1e40af,stroke-width:1px,color:#0f172a;
    classDef edge fill:#cffafe,stroke:#0e7490,stroke-width:1px,color:#0f172a;
    classDef service fill:#fef3c7,stroke:#92400e,stroke-width:1px,color:#0f172a;
    classDef datastore fill:#fee2e2,stroke:#991b1b,stroke-width:1px,color:#0f172a;
    classDef cache fill:#fed7aa,stroke:#9a3412,stroke-width:1px,color:#0f172a;
    classDef queue fill:#ede9fe,stroke:#5b21b6,stroke-width:1px,color:#0f172a;
    classDef compute fill:#d1fae5,stroke:#065f46,stroke-width:1px,color:#0f172a;
    classDef storage fill:#e5e7eb,stroke:#374151,stroke-width:1px,color:#0f172a;
    classDef external fill:#fce7f3,stroke:#9d174d,stroke-width:1px,color:#0f172a;
    classDef obs fill:#f3e8ff,stroke:#6b21a8,stroke-width:1px,color:#0f172a;
    class GW edge;
    class PSVC,SELLER,PRICE,SRCH,HOME,CART,CKT,PROMO,EMI,UPI,PAY,PG,OSVC,INV,OMS,SHIP,HUB,LASTM,TRK,PRE,THROT,RES,RET,REF,SUP service;
    class PDB,INVIDX,INVDB datastore;
    class LANE queue;
    class REC,SAGA compute;

Specifics vs global Amazon

• UPI-first payments in India; many low-cost prepaid methods.
• Cash on Delivery still common — affects RTO (return-to-origin) economics.
• Big-sale events require pre-warming, ticketed queues, reservation TTLs.
• Logistics integrated: Ekart owns last mile; tighter integration than 3PL.

Glossary & fundamentals

Concepts referenced in this design. Each row links to its canonical page; the tag column shows whether it is a high-level (HLD) or low-level (LLD) concept.

Tag	Concept	What it is	Page
HLD	Load balancer / GSLB	L4/L7 traffic distribution and failover	load-balancer
HLD	CDN	edge caching for static assets	cdn
HLD	Distributed transactions	2PC, TCC, sagas, outbox/inbox	distributed-transactions
HLD	Search internals	inverted index, BM25, embeddings, ANN	search-internals
HLD	Multi-region & DR	RTO / RPO, active-active, failover	multi-region-dr