runtime-cache

Import getCache from @vercel/functions, then call cache.set with a key, value, TTL, and tags. Use cache.get to retrieve values and cache.delete to remove specific keys. The cache is regional and shared across functions in the same project and deployment environment.

Call cache.expireTag with one or more tags to invalidate Runtime Cache entries, propagating globally within 300ms. To purge across CDN, Runtime, and Data caches together, use invalidateByTag for stale-while-revalidate or dangerouslyDeleteByTag for hard deletion.

'use cache' stores data in-memory per instance and is ephemeral. 'use cache: remote' stores data in the Vercel Runtime Cache, making it persistent across deployments and shared across function instances in a region.

No. Next.js revalidateTag and revalidatePath do not invalidate the Runtime Cache, and cache.expireTag does not invalidate ISR pages. To purge all cache layers with one tag, use invalidateByTag from @vercel/functions.

Items are limited to 2 MB, with up to 64 tags per Runtime Cache item and 128 per CDN item. Tags are case-sensitive, cannot contain commas, and are capped at 256 bytes. The cache is ephemeral with LRU eviction when full.

Avoid it for persistent storage, cross-region shared state, or user-specific data that varies per request. Use a database like Neon or Upstash for persistence, Cache-Control headers for CDN-level response caching, and Next.js Cache Components for framework-level page caching.