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[System Design Tech Case Study Pulse #90] 2 Billion Users and Billions of Messages Daily : How Whatsapp Actually Works
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[System Design Tech Case Study Pulse #90] 2 Billion Users and Billions of Messages Daily : How Whatsapp Actually Works

Behind the tech with detailed explanation and flow chart....

Naina Chaturvedi's avatar
Naina Chaturvedi
Jun 19, 2025
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[System Design Tech Case Study Pulse #90] 2 Billion Users and Billions of Messages Daily : How Whatsapp Actually Works
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Hi All,

WhatsApp's ability to handle billions of messages daily across the globe is a testament to its highly sophisticated and scalable messaging infrastructure. This feat requires an intricate system of distributed services, real-time processing engines, and intelligent routing algorithms working in perfect harmony to ensure instant message delivery and seamless communication for over 2 billion users worldwide.

Let's dive deep into how WhatsApp engineered this complex system, exploring the key architectural decisions, scaling strategies, and optimizations that enabled their global messaging dominance.

Learn how to Design Facebook Newsfeed


System Overview 

Before we delve into WhatsApp's messaging infrastructure technology, let's look at some key metrics that highlight the scale of their operations:

- Daily active users: 2 billion+

- Messages sent per day: 100 billion+

- Peak messages per second: 10 million+

- Countries served: 180+

- Languages supported: 60+

- Data centers: 50+ globally

- Server instances: 500,000+

- Database transactions per second: 200 million+

- Storage capacity: Petabytes

- Network bandwidth: 500+ Tbps

- End-to-end encrypted messages: 100%

- Availability: 99.99%


How Real World Scalable Systems are Build — 200+ System Design Case Studies:

System Design Den : Must Know System Design Case Studies

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20 Billion Messages Daily: How Facebook Messenger Actually Works

8+ Billion Daily Views: How Facebook's Live Video Ranking Algorithm Works

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80 Million Photos Daily : How Instagram Achieves Real Time Photo Sharing

Serving 1 Trillion Edges in Social Graph with 1ms Read Times : How Facebook TAO works

How Lyft Handles 2x Traffic Spikes during Peak Hours with Auto scaling Infrastructure..

How It works (Behind the Tech ) —

1. The Sender composes a message in the WhatsApp App. The app connects to WhatsApp's servers through the Global Load Balancer, which routes the connection to the nearest data center.

2. The Connection Manager establishes and maintains a persistent connection with the sender's device. It also updates the Presence System about the user's online status.

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