System requirements

Functional:

Write Post

Post Post

Share Tweets

Follow Users

View news feed

Like and react to posts

Follow and unfollow users

Account Authentication

Non-Functional:

Eventual Consistency on News Feed

Low Latency

Highly availability

Highly reliable

Fault tolerance

Capacity estimation

Let's assume 300,000,000 MAU

Unique DAU 10,000,000

Peak concurrent users: 1,000,000

QPS: 1,500,000

This would be a Read heavy system. Let's assume 40% of QPS are Writes: posts, likes, comments and the other 60% are Reads

API design

Define what APIs are expected from the system...

Database design

Defining the system data model early on will clarify how data will flow among different components of the system. Also you could draw an ER diagram using the diagramming tool to enhance your design...

High-level design

You should identify enough components that are needed to solve the actual problem from end to end. Also remember to draw a block diagram using the diagramming tool to augment your design. If you are unfamiliar with the tool, you can simply describe your design to the chat bot and ask it to generate a starter diagram for you to modify...

Request flows

Explain how the request flows from end to end in your high level design. Also you could draw a sequence diagram using the diagramming tool to enhance your explanation...

Detailed component design

Dig deeper into 2-3 components and explain in detail how they work. For example, how well does each component scale? Any relevant algorithm or data structure you like to use for a component? Also you could draw a diagram using the diagramming tool to enhance your design...

Trade offs/Tech choices

Explain any trade offs you have made and why you made certain tech choices...

Failure scenarios/bottlenecks

Try to discuss as many failure scenarios/bottlenecks as possible.

Future improvements

What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?