Jump to a problem, path or page
Jump to a problem, path or page
Start here for architecture
Core request paths, durable state, caches and async side effects on approachable problems. Finish this before the advanced HLD paths.
Turn long URLs into short links. Keep redirects fast when a link goes viral.
Deliver email, SMS, and push notifications without losing work during provider outages.
Design resumable uploads, durable metadata and secure downloads for large files.
Route requests with authentication, quotas and bounded downstream failure handling.
Evaluate consistent rollouts with versioned rules and predictable outage defaults.
Maintain ordered scores with deduplicated updates, seasons and deterministic ties.
Track multi-device presence using heartbeats, expiry and stale-event protection.
Serve ranked prefix suggestions while rebuilding indexes without downtime.
Transform uploads into immutable variants with bounded decoding and retryable jobs.
Find nearby places using spatial candidates, exact distance filtering and bounded queries.
Accept one logical vote per participant and publish recoverable live aggregates.
Deliver ordered conversations across devices, reconnects and offline recipients.
Share document revisions with optimistic concurrency, resumable history and access revocation.