Google Maps — Detailed

flowchart TB
  subgraph Clients
    BR
    APP([Mobile / Auto])
    EMB[Embed API]
  end

  subgraph Edge
    CDN
    GW
  end

  subgraph Tiles[Map Tiles]
    TS[Tile Service]
    RAS[Raster tiles 256/512]
    VEC[Vector tiles]
    Z[Zoom levels 0-22]
    PROJ[Mercator projection]
    CACHE[(Tile cache on CDN)]
  end

  subgraph Data[Map Data]
    OSM([Ground truth ingest<br/>sat imagery, OSM, vendors])
    EDIT[Editor + ops tools]
    BUILD[Tile build pipeline]
    GEO[(Spatial DB - S2 cells)]
  end

  subgraph Places[Places & Geocoding]
    PSVC[Places Service]
    GEOC[Geocoder]
    REV[Reverse geocoder]
    PIDB[(POIs DB)]
    SRCH[Place search]
  end

  subgraph Route[Routing & ETA]
    R1[Route Service]
    GRAPH[(Road graph<br/>contraction hierarchies)]
    CH[CH preprocessor]
    DIJK[A* / Dijkstra]
    ETA[ETA model]
    TRAF[[Live traffic stream]]
    HIST[Historical traffic]
  end

  subgraph Live[Live signals]
    PROBES([GPS probes from phones])
    SPEED[Speed estimation]
    INCID[Incidents / closures]
  end

  subgraph Nav[Turn-by-turn navigation]
    SES[Nav session]
    REROUTE[Reroute on miss]
    LANE[Lane guidance]
    VOICE[Voice TTS]
  end

  Clients --> CDN --> GW
  GW --> Tiles --> CACHE
  Tiles -. miss .-> TS
  TS --- Data
  GW --> Places --> PIDB
  GW --> Route --> GRAPH
  Route --> DIJK
  Route --> ETA
  TRAF --> ETA
  PROBES --> SPEED --> TRAF
  HIST --> ETA
  Route --> Nav
  Live --- Route

    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 APP,PROBES client;
    class EMB,TS,RAS,VEC,Z,PROJ,EDIT,BUILD,PSVC,GEOC,REV,SRCH,R1,CH,DIJK,ETA,HIST,SPEED,INCID,SES,REROUTE,LANE,VOICE service;
    class CACHE,GEO,PIDB datastore;
    class TRAF queue;
    class OSM compute;

Tiles

• Pre-rendered raster or thin vector tiles, served via CDN.
• Tile key = (z, x, y). Higher z = closer zoom; tile count quadruples per level.

Routing

• Road network as a graph; preprocessed with Contraction Hierarchies for fast queries.
• Online A* with edge-weight = f(distance, current_speed, predicted_speed).
• For long routes: hierarchy of "important" edges (highways pre-computed).

ETA model

• Inputs: distance, speed limits, live traffic, weather, historical patterns, time of day.
• ML regressor; updated minutely.

Live traffic

• GPS probes from millions of phones (privacy-aggregated).
• Map-match probes to road segments; compute speed.
• Detect incidents (cluster of slowdowns).

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	CDN	edge caching for static assets	cdn
HLD	Geo indexing	Geohash, Quadtree, S2, H3, R-tree	geo-indexing