Caching Strategies

Caching is one of the highest-leverage frontend performance techniques — it reduces load times, server load, and improves scalability across every layer of the stack.

This module covers the four caching layers, six core cache strategies, browser storage options, API caching with TanStack Query and SWR, and the best practices SDE-2 interviews expect.

You will understand cache invalidation trade-offs, when stale-while-revalidate beats cache-first, how CDN edge caching interacts with Cache-Control headers, and how to avoid serving stale or sensitive data to the wrong user.

Layers covered: browser HTTP cache, CDN, application cache (Redis), database query cache, Service Worker strategies, and client libraries like TanStack Query — each with headers, patterns, and interview comparisons.