Step 1 of 12 · Intro

Design a proximity service (nearby search)

Turn latitude and longitude into fast 'near me' lookups for millions of people.

How it works

• ›Search: given a position and radius, return nearby places.
• ›Details: open one place.
• ›Update: owners add or move places; users may also share live positions.

What you'll build

1. The API and a geohash-based data model
2. Caching and a CDN keyed by map cell
3. A geo index and a write-behind cache for location updates
4. Sharding by region
5. A design that survives a cold cache and a lost index node