CDN cache. For caching build artifacts, see Remote cache.

When to use runtime cache

Runtime cache is best when your functions fetch the same data multiple times or perform expensive computations that can be reused, such as in the following scenarios:

• API calls that return the same data across multiple requests
• Database queries that don't change frequently
• Expensive computations you want to reuse
• Data fetching in server components or API routes

Runtime cache is not a good fit for:

• User-specific data that differs for each request
• Data that must be fresh on every request
• Data that must be retained for its full TTL (entries may be evicted sooner if the cache reaches its storage limit)
• Complete HTTP responses (use CDN cache instead)

How runtime cache works

Runtime cache stores data in a non-durable cache close to where your function executes. Each region where your function runs has its own cache, allowing reads and writes to happen in the same region for low latency. It has the following characteristics:

• Regional: Each region has its own cache
• Isolated by environment: Each deployment environment ( preview and production) uses its own cache, so they never share cached data
• Scoped by plan: On Pro and Enterprise, each project uses its own cache. On Hobby, all projects in your team share a single cache. See storage scope by plan
• Persistent across deployments: Cached data persists across deployments and can be invalidated through time-based expiration or by calling expireTag
• Ephemeral: Each cache has a storage limit. When a cache reaches this limit, Vercel evicts (removes) the entries that haven't been accessed recently to free up space for new entries
• Automatic: When runtime cache is enabled, Vercel handles caching for you
• Framework-agnostic: Works with all frameworks

The cache sits between your function and your data source, reducing the need to repeatedly fetch the same data. See limits and usage for information on item size, tags per item, and maximum tag length.

Using runtime cache

You can cache your Vercel function with any framework by using the functions of the helper method getCache.

Runtime cache with any framework

This example caches data fetched from the API so that it expires after 1 hour and adds a tag to the cache entry so you can invalidate it later from code:

• use cache: remote: A directive that caches entire functions or components with Runtime cache. Requires enabling cacheComponents in your config.
• fetch with force-cache: Caches individual fetch requests without additional configuration with Data cache.

Using use cache: remote

Use the use cache: remote directive at the file, component, or function level to cache the output of a function or component.

use cache is in-memory by default. This means that it is ephemeral, and disappears when the instance that served the request is shut down. use cache: remote is a declarative way telling the system to store the cached output in a remote cache such Vercel runtime cache.

First, enable the cacheComponents flag in your next.config.ts file:

importtype { NextConfig } from'next';

constnextConfig:NextConfig= {

cacheComponents:true,

};

exportdefault nextConfig;

Then, use the use cache: remote directive in your code. This example caches data so that it expires after 1 hour and adds a tag to the cache entry so you can invalidate it later from code: