Next.js App Router Caching: Choosing the Right Strategy Before Reaching for Flags

Next.js App Router provides four caching layers — Request Memoization, Data Cache, Full Route Cache, and Router Cache — each serving a distinct purpose in managing data freshness. A common mistake among developers is reaching for configuration flags like force-dynamic or no-store without first defining how stale a given piece of data can acceptably be. The author argues that caching decisions should start with a 'data contract' — a clear agreement on acceptable data age — rather than trial-and-error with API options. For example, revalidate suits editorial content updated infrequently, while force-dynamic is appropriate for fully personalized or real-time data but carries a higher server rendering cost per request. Using cache: 'no-store' at the individual fetch level offers a more surgical alternative when only one data source in a component needs to bypass caching entirely.