Design Problems

Turn long links into short codes and redirect billions of clicks with low latency.

Store and share text snippets with expiry and optional privacy.

Generate globally unique, roughly time-ordered 64-bit IDs without a central bottleneck.

Rank millions of players by score and serve top-N and my-rank queries in milliseconds.

Enforce per-client request limits consistently across a fleet of API servers.

Deliver push, SMS, and email notifications reliably with user preferences and rate caps.

Build a personalized home feed that stays fast even when celebrities post.

Upload, process, and serve photos at scale with follows, likes, and a feed.

Crawl billions of pages politely, avoid duplicates, and keep content fresh.

Suggest popular completions as users type, within tens of milliseconds.

Find nearby businesses within a radius for hundreds of millions of users.

Run millions of scheduled and recurring jobs on time, at least once, without duplicates.

Collect, store, query, and alert on millions of time series.

Build a Dynamo-style store that stays available through node failures.

Deliver one-to-one and group messages in real time with offline sync and receipts.

Ingest, transcode, and stream video to millions of concurrent viewers.

Sync files across devices efficiently with deduplication and versioning.

Track drivers in real time and match riders to nearby drivers within seconds.

Sell seats for hot events without double-booking under massive flash-sale traffic.

Move money correctly through external processors with a double-entry ledger.

Count billions of ad clicks per day in near real time with accurate billing totals.

Let many users edit the same document simultaneously and converge on one result.