Caching

Use HTTP caching headers. The server controls cache policy; the client honors it.

Immutable assets (versioned JS/CSS/images):

Cache-Control: public, max-age=31536000, immutable

Dynamic but cacheable (API responses):

Cache-Control: private, max-age=60

MUST NOT cache (sensitive data, mutations):

Cache-Control: no-store

Conditional requests — use ETags to avoid re-downloading unchanged data:

1. Server sends ETag: "abc123"
2. Client revalidates with If-None-Match: "abc123"
3. Server responds 304 Not Modified (no body) or 200 with new data

Client-side invalidation:

• After mutations (POST/PUT/DELETE), related cache entries MUST be invalidated
• Stale-while-revalidate: serve cached data immediately, refresh in background
• Framework support: React Query, SWR, Apollo Client all handle this natively

References:

• RFC 9111: HTTP Caching
• web.dev: HTTP Cache
• MDN: Cache-Control

Change History