Initial version of Google Maps Design by ganeshkumarm1 · Pull Request #20 · SweetCodey/system-design-masterclass

ganeshkumarm1 · 2026-03-03T16:46:57Z

Completed Intro, Requirements, Rendering, and Routing sections
To work on Search and Dive Deep Insights
Added TK place holder for sections that has to be updated

1. Completed Intro, Requirements, Rendering, and Routing sections 2. To work on Search and Dive Deep Insights 3. Added TK place holder for sections that has to be updated

SweetCodey · 2026-03-05T16:52:20Z

15. Design Google Maps/GoogleMaps.md

+* **Low Latency** – Search, tile loading, and routing responses must be with in 100 ms.
+* **High Availability** – Core features should remain 99.99% during peak usage.
+* **Scalability** – System must handle millions of concurrent users.
+* **Geospatial Accuracy** – Location tracking and routing must be precise with an acceptable error of + or - 100 meters.


100m might be a lot of distance. Can we reduce it to 40m?

SweetCodey · 2026-03-05T19:23:36Z

15. Design Google Maps/GoogleMaps.md

+
+---
+
+## API Design


Can we add an explanation about why we use protobuf here? One to two line explanation is also fine.

SweetCodey · 2026-03-05T19:25:15Z

15. Design Google Maps/GoogleMaps.md

+
+The response will be binary data (pbf - Protocolbuffer Binary Format) containing layers such as roads, buildings, water, and places. Since it is binary, we cannot visualize the response. But after decoding, it looks something like below:
+
+```json


I'm failing to understand the response in simple language. Could it be possible to explain it a bit? 2-3 lines explanation is also fine.

Yes. will ad it

SweetCodey · 2026-03-05T19:27:24Z

15. Design Google Maps/GoogleMaps.md

+
+### Routing
+
+Routing finds the fastest possible route from source to destination and provides turn by turn instructions to reach the destination. This is the core "Point A to Point B" service. It uses algorithms on the static road graph to return a polyline (a compressed string of coordinates).


Can we simplify the language here? Especially 3rd line seems to be rather complex.

SweetCodey · 2026-03-06T19:39:16Z

15. Design Google Maps/GoogleMaps.md

+
+**HTTP Response**
+
+The response contains an array consisting of multiple routes sorted in the order of durationSeconds (ETA) ascending.


The response still seems confusing. Can you explain in one to two more lines?

SweetCodey · 2026-03-06T19:40:46Z

15. Design Google Maps/GoogleMaps.md

+```
+
+## High Level Design
+Below are some of the terms we frequently come across in the upcoming sections of the document.


Can we add images or diagrams for each of the below? Even small images or diagrams are fine.

SweetCodey · 2026-03-06T19:49:59Z

15. Design Google Maps/GoogleMaps.md

+
+Because this work happens ahead of time, opening the map does not require image processing. The client simply requests the tiles needed for the current viewport.
+
+![](Resources/HLD_Rendering_Capture.png)


Didn't understand much from this image and the above steps. Can you try relating those steps to this image? That could help in better understanding.

SweetCodey · 2026-03-06T20:04:05Z

15. Design Google Maps/GoogleMaps.md

+
+![](Resources/HLD_Rendering_Vector.png)
+
+Vector geometry is typically stored in spatial databases such as PostgreSQL with the PostGIS extension. During preprocessing, this geometry is organized into vector tiles, where each tile contains only the features that intersect that region and zoom level. These tiles are stored in object storage and served through CDNs, making them highly cacheable and efficient to distribute.


Didn't understand this part: 'PostgreSQL with the PostGIS extension'

SweetCodey · 2026-03-06T20:07:37Z

15. Design Google Maps/GoogleMaps.md

+
+#### End-to-End Rendering Flow
+
+![](Resources/HLD_Rendering_Flow.png)


Why do we have two API gateways?

Good catch. It is not needed. Will fix it

SweetCodey · 2026-03-09T21:49:34Z

15. Design Google Maps/GoogleMaps.md

+
+---
+
+## API Design


Requirements had "Real-time Navigation i.e. continuously track user location and re-route." HLD also describes GPS updates every few seconds. But no API is defined for this. Can you work on adding it?

SweetCodey · 2026-03-09T22:59:05Z

15. Design Google Maps/GoogleMaps.md

+---
+
+## API Design
+### Search


Can we paginate? Might be needed as we might get 100s of results for search.

SweetCodey · 2026-03-09T23:00:30Z

15. Design Google Maps/GoogleMaps.md

+* **Route Calculation** – Compute a path between source and destination.
+* **Real-time Navigation** – Continuously track user location and re-route if needed.
+
+### Non-Functional Requirements


Each NFR states a number but doesn't explain why it matters for a maps system specifically. Can we add one sentence per NFR explaining the consequence? E.g., "If tiles load slowly, the map feels laggy when users pan or zoom."

SweetCodey · 2026-03-10T01:36:57Z

15. Design Google Maps/GoogleMaps.md

+
+![](Resources/HLD_Search.png)
+
+1. User enters a query (e.g., "coffee shops") and the client sends a `GET /v1/places/search` request with query text, and user's GPS location


GPS coordinates are sensitive PII. Consider a brief note about encryption in transit and retention policies.

SweetCodey · 2026-03-10T01:48:35Z

15. Design Google Maps/GoogleMaps.md

+#### 1. How does the system translate text into geographic coordinates
+When a user searches for a specific location (for example **"Marina Beach"**), the system needs to convert that text into geographic coordinates. This process is called **Forward Geocoding**. Forward geocoding simply means converting human-readable text into **latitude and longitude**. For example, *"Marina Beach"* is translated into "13.0500° N, 80.2824° E"
+
+> Similar to Forward Geocoding, there exists **Reverse Geocoing** where user taps a location on a map and get the place details.


nit: "Reverse Geocoing" → "Reverse Geocoding" (typo)

SweetCodey · 2026-03-10T01:50:03Z

15. Design Google Maps/GoogleMaps.md

+
+**A\*  (A-Star)**
+
+Assume you are driving from Chennai Airport to Marina Beach. The road network includes small residential streets, arterial roads, and highways. If we ran Dijsktra, it would expand in all directions even though Marina Beach lies northeast of the airport.


nit: "Dijsktra" is misspelled. It should be "Dijkstra". More such typos are there

SweetCodey · 2026-03-10T01:50:44Z

15. Design Google Maps/GoogleMaps.md

+
+**Contraction Hierarchies**
+
+Assume another scenario, where you are driving from Chennai to Bengaluru. The road netwrok includes thousands of local streets, city arterial roads, and national highways. In reality, long-distance travel looks like: `local road → city arterial → National highway → city arterial → local road`. So, you do not evaluate every residential street between the two cities.


nit: "road netwrok" → "road network". More such typos are there

SweetCodey · 2026-03-10T01:51:49Z

15. Design Google Maps/GoogleMaps.md

+
+#### 3. How does navigation adjust in real time
+
+Consider a scenario where you are driving from Chennai Airport to T Nagar during evening traffic. The initial route is `Airport → GST Road → Kathipara → Anna Salai → T Nagar` and the estimated time is **40 mins**. While you drive, your phone sends location updates every few seconds via GPS (Global Positioning System). Each update contains atitude, longitude, speed, and direction. 


nit: "atitude" → "latitude"

Initial version of Google Maps Design

0e6df4c

1. Completed Intro, Requirements, Rendering, and Routing sections 2. To work on Search and Dive Deep Insights 3. Added TK place holder for sections that has to be updated

SweetCodey requested changes Mar 7, 2026

View reviewed changes

ganeshkumarm1 added 2 commits March 7, 2026 23:24

Added Search design and addressed review comments

d57c8a7

Added Deep Dive sections and minor corrections

1584e29

SweetCodey requested changes Mar 10, 2026

View reviewed changes

Addressed final review comments

15edef0

SweetCodey merged commit 335c85b into main Mar 10, 2026
1 check failed


		The response will be binary data (pbf - Protocolbuffer Binary Format) containing layers such as roads, buildings, water, and places. Since it is binary, we cannot visualize the response. But after decoding, it looks something like below:

		```json


		### Routing

		Routing finds the fastest possible route from source to destination and provides turn by turn instructions to reach the destination. This is the core "Point A to Point B" service. It uses algorithms on the static road graph to return a polyline (a compressed string of coordinates).


		HTTP Response

		The response contains an array consisting of multiple routes sorted in the order of durationSeconds (ETA) ascending.


		Because this work happens ahead of time, opening the map does not require image processing. The client simply requests the tiles needed for the current viewport.

		![](Resources/HLD_Rendering_Capture.png)


		![](Resources/HLD_Rendering_Vector.png)

		Vector geometry is typically stored in spatial databases such as PostgreSQL with the PostGIS extension. During preprocessing, this geometry is organized into vector tiles, where each tile contains only the features that intersect that region and zoom level. These tiles are stored in object storage and served through CDNs, making them highly cacheable and efficient to distribute.


		#### End-to-End Rendering Flow

		![](Resources/HLD_Rendering_Flow.png)


		![](Resources/HLD_Search.png)

		1. User enters a query (e.g., "coffee shops") and the client sends a `GET /v1/places/search` request with query text, and user's GPS location


		*A\ (A-Star)**

		Assume you are driving from Chennai Airport to Marina Beach. The road network includes small residential streets, arterial roads, and highways. If we ran Dijsktra, it would expand in all directions even though Marina Beach lies northeast of the airport.


		Contraction Hierarchies

		Assume another scenario, where you are driving from Chennai to Bengaluru. The road netwrok includes thousands of local streets, city arterial roads, and national highways. In reality, long-distance travel looks like: `local road → city arterial → National highway → city arterial → local road`. So, you do not evaluate every residential street between the two cities.


		#### 3. How does navigation adjust in real time

		Consider a scenario where you are driving from Chennai Airport to T Nagar during evening traffic. The initial route is `Airport → GST Road → Kathipara → Anna Salai → T Nagar` and the estimated time is 40 mins. While you drive, your phone sends location updates every few seconds via GPS (Global Positioning System). Each update contains atitude, longitude, speed, and direction.

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ganeshkumarm1 commented Mar 3, 2026

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