System requirements

Functional:

1. Take in a url and create a shortened version
2. redirect from a given shortened URL to the original long URL
3. keep track of the shortened URL usage
4. create custom URLs
5. shortened URLs should be unpredictable and unique
6. shortened URLs should work for at least 1 year
7. return user to home page with a simlpe error if shortened URL doesn't work

Non-Functional:

1. assume this is a moderate service with about 1Million users a day
2. each short URL has about 3-5 clicks
3. support about 5 million redirects each day
4. Users can post to websites and social media so likely need to serve resources globally
5. Redirects should happen in less than 2 seconds median time

Capacity estimation

1000000 urls a day, or 365Million shortened urls a year

average shortened and long URL pair is about 200 characters, or 200 bytes total. Annual storage for a single data store should be 70,000,000,000 bytes or about 70 GB annually. likely will need some replication in key geographies, say europe, us, and japan. Total annual data storage should be about 210 GB

API design

Need at least an API server with a POST that takes

Database design

Use a in-memory key-value store like Redis or MemCached in order to store the values. Each of the Key-Values Stores should be hosted in a region (i.e. US, Europe, and Japan). Each server should be eventual consistent with each other using replication of the shortened URLs. If a hashing algorithm isn't unique enough, then each region should have a simple prepended string to ensure uniqueness in the moment

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?