Caching Strategies: Client, Server & Edge
Learn the interview-ready mental model, practical trade-offs, and production patterns for this web fundamentals topic.
Topic content
Caching reduces latency and backend load but introduces consistency challenges. Choose the right layer — client memory, browser storage, server cache (Redis), or edge/CDN — based on data volatility, scope, and freshness requirements.
Memory cache is your quick personal notepad (fastest). LocalStorage is your desk drawer (persists across reloads). Redis is a shared office whiteboard (accessible by everyone). CDN is local warehouses around the world (fast global delivery). The best system uses the right notebook for each type of information.
1Client-Side Caching
Memory (React Query/Zustand) for session data, LocalStorage for preferences, IndexedDB for large/offline data, Service Worker for full offline support.
2Server-Side & Edge Caching
Redis for shared state and query results. CDN for static assets and global latency reduction.
3Invalidation Strategies
Time-based (TTL), event-based (pub/sub), version-based (cache busting), and stale-while-revalidate.
- ✓Cache at multiple layers for best results
- ✓Memory for speed, CDN for global reach, Redis for shared state
- ✓Define freshness guarantees before choosing TTLs
- ✓Plan invalidation strategy (time, event, versioning)
- ✓Monitor cache hit rates and consistency
- ✓Separate static assets from dynamic data
- ✓Caching is about consistency first, speed second