Design a Url Shortener service like bit.ly

Design Url Shortener

A rate limiter is a system is to prevent a user from making too many requests to a service within a certain time frame. This is used to protect services from abuse and can be implemented in various scopes like per user, per IP address, etc.


Design Rate Limiter

Design a coding contest platform like LeetCode.

Design LeetCode

Yelp is an online platform that publishes crowd-sourced reviews about businesses. It also trains small businesses to respond to reviews responsibly; hosts social events for reviewers; and provides data about businesses, including health inspection scores. Yelp.com is a popular platform for users to find and review new places to eat, shop, drink, relax, and play.


Design Yelp

Pastebin is an online application where users can store plain text. It is often used by developers to store pieces of sources code or configuration information, but anyone can essentially store any type of text. The idea behind the site is to make it more convenient for people to share large amounts of text online. Each piece of text that is pasted on Pastebin can be accessed through a unique URL


Design Pastebin

Design E-commerce Store

Design a realtime server monitoring and alert system like Datadog.

Design Realtime Monitoring System

A typeahead system, often called autocomplete, is a feature in software programs that predicts the rest of a word or phrase that a user is typing. This functionality helps users to find and select from a pre-populated list of values as they type, reducing the amount of typing needed and making the input process faster and more efficient.

An everyday example of a typeahead system is Google's search box. As you begin typing your search query, Google provides a dropdown list of suggested search terms that match what you have typed so far. These suggestions are based on popular searches and the content indexed by Google's search engine. This allows you to see and select your intended search without having to type out the entire term, making the search process faster and more efficient.

When a user begins to type in the search box, the typeahead feature could suggest book titles, authors, or genres that match the typed characters. For instance, if the user types in "Har", the system could suggest "Harry Potter", "Harper Lee", etc. This kind of typeahead system can greatly enhance the user experience by providing instant feedback and helping users formulate their search queries.

In this problem, we will design a typeahead system for a large e-commerce site. The system will provide search suggestions to users as they type in the search box. The suggestions will be based on the most popular searches and the content indexed by the e-commerce site's search engine.


Design Typeahead System

Design a comment system, such as Disqus, is a feature integrated into websites that allows users to post comments on published content, interact with other users through replies, upvote or downvote comments, and sort or filter comments. This system must be robust, scalable, and efficient to handle a large volume of users and comments.

Design a Comment System

Design a simplified version of Twitter where users can post tweets, follow/unfollow other users and is able to see the tweets of its followings.

Design Twitter

Design a Realtime Chat App like WhatsApp

Design a file hosting service such as Dropbox or Google Drive.
A cloud file hosting service allows users to upload, download, and share files across different platforms.
It should support multiple file types including text, images, and multimedia formats.
For this problem let's focus on the backend system that stores and syncs them between different devices.


Design Dropbox

YouTube is an online video-sharing platform where users can upload, share, and view videos. It supports various types of videos, including TV show clips, music videos, short and documentary films, movie trailers, and other content such as video blogging (vlogging), short original videos, and educational videos.


Design YouTube

Design a Ride-Hailing Service Like Uber

Design a mapping service like Google Maps

Design Google Maps

Design a event ticketing system like TicketMaster

Design TicketMaster

Netflix is a streaming service offering a wide array of TV shows, movies, anime, documentaries, and more on thousands of internet-connected devices. Unlike YouTube, which primarily hosts user-generated content, Netflix focuses on delivering professionally produced film and television content, providing users with access to a vast library of titles without the need to watch a single commercial.


Design Netflix

For a platform like Spotify, design a sytem that returns the top K songs played in the last 7 days. The same solution can also be applied to getting the top K most popular items of an e-commerce platform.


Problems