Challenge library
Each brief is a real interview scenario with stated traffic, latency budgets, and failure expectations. Draw your design on the canvas and get scored against it.
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Turn long URLs into short ones and redirect them fast, in the style of TinyURL or bit.ly.
Stop a single client from hammering your API with more requests than it is allowed.
Build one-to-one and group messaging in the style of WhatsApp, Slack, or Discord.
Build video upload, transcoding, and playback in the style of Netflix or YouTube.
Track drivers by location and match them to riders, in the style of Uber or Lyft.
Build an in-memory key-value cache cluster with eviction and replication, in the style of Redis.
Generate a personal social feed at high volume, in the style of Twitter/X or the Facebook News Feed.
Fetch and store billions of pages for a search index.
Send push, SMS, email, and in-app notifications from one service.
Store files in the cloud and sync them across devices, in the style of Google Drive or Dropbox.
Return search suggestions as the user types, in the style of Google or Amazon.
Sell a limited stock to a huge crowd without overselling it.
Take in millions of metrics a second, store them in time order, and alert on them.
Build a text editor several people can type in at once, in the style of Google Docs or Notion.
Hand out unique 64-bit IDs that sort by time, the Snowflake problem.
Serve top scores and rank lookups for millions of players, live.