System Design: WhatsApp
In this lesson1 sections
System Design: WhatsApp
Design a messaging service in which people can exchange text and media even when their devices reconnect frequently. The central questions are when a message is safe to acknowledge, how it reaches each intended device, and what the service retains while a recipient is offline.
WhatsApp supports text, voice, and multimedia messaging. We will use these capabilities to define an interview design, with an explicit delivery and encryption model.
WhatsApp announced more than two billion users in February 2020. That is historical context, not a current DAU figure. The source chart also illustrates historical message-volume growth. The next lesson adopts 100 billion messages per day as a hypothetical sizing workload; the proposed components are not a verified inventory of WhatsApp’s current backend.
The increase in messages sent globally per day is depicted in the following chart:
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