You're right. There is no direct built-in replacement specifically for the "next-boost" package in Next.js 15.

To clarify:

1. "next-boost" is a third-party package that provides server-side caching for Next.js applications, particularly for the Pages Router.
2. While Next.js 15 has introduced several performance improvements and caching mechanisms, it doesn't include a direct equivalent to next-boost's specific implementation of server-side caching with Redis/LRU cache.

If you're using "next-boost" for server-side caching in a Pages Router application, you would still need to continue using it or consider these alternatives:

1. Use Vercel's Edge Middleware for caching responses
2. Implement custom caching using Route Handlers in the App Router
3. Use a CDN with proper cache configuration
4. Consider other caching libraries like cachified or @vercel/edge-config for edge caching

Next.js 15 has improved its built-in caching mechanisms, but for the specific server-side caching functionality that "next-boost" provides, you would still need a separate solution or package.

Server-Side Caching Solutions for Next.js 15

Since you need a replacement for next-boost's server-side caching functionality, here are practical solutions you can implement in Next.js 15:

1. Route Handler with Redis Caching

This approach uses App Router Route Handlers with Redis for server-side caching:

2. Edge Middleware Caching

For edge caching similar to next-boost, you can use Vercel's Edge Middleware:

3. Server Actions with Caching

For a more modern approach using Server Actions with caching:

4. Vercel KV with Edge Config

For a more scalable solution using Vercel's KV and Edge Config:

Installation Instructions

To implement any of these solutions, you'll need to:

1. Install dependencies:

2. Set up environment variables in your .env.local file:

3. Deploy to Vercel to take advantage of Edge Functions and KV storage.

These solutions provide similar functionality to next-boost but are designed to work with Next.js 15's App Router and modern caching patterns.

This generation may require the following integrations:

Please make sure to add the following environment variables to your project: