Caching

Caching is the most common performance optimization in web development. Instead of querying the database on every request, you store the result in a fast layer and serve it from there. When the underlying data changes, you invalidate the cache so the next request fetches fresh data.

Caching happens at multiple levels: browser cache (HTTP headers), CDN cache (Cloudflare, Vercel Edge), application cache (Redis, in-memory), and database cache (query result caching). Each level trades freshness for speed.

For vibe coders, caching is where AI-generated code often needs human judgment. AI can add caching to an endpoint, but deciding what to cache, for how long, and how to invalidate it requires understanding your specific data and user patterns. A cache with the wrong TTL or no invalidation strategy creates stale data bugs that are hard to track down.