Going to Production

Before taking your Next.js application to production, here are some recommendations to ensure the best user experience.

• Use caching wherever possible.
• Ensure your database and backend are deployed in the same region.
• Aim to ship the least amount of JavaScript possible.
• Defer loading heavy JavaScript bundles until needed.
• Ensure logging is set up.
• Ensure error handling is set up.
• Configure the 404 (Not Found) and 500 (Error) pages.
• Ensure you are measuring performance.
• Run Lighthouse to check for performance, best practices, accessibility, and SEO. For best results, use a production build of Next.js and use incognito in your browser so results aren't affected by extensions.
• Review Supported Browsers and Features.
• Improve performance using:
  • next/image and Automatic Image Optimization
  • Automatic Font Optimization
  • Script Optimization

Caching improves response times and reduces the number of requests to external services. Next.js automatically adds caching headers to immutable assets served from /_next/static including JavaScript, CSS, static images, and other media.

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

Cache-Control headers set in next.config.js will be overwritten in production to ensure that static assets can be cached effectively. If you need to revalidate the cache of a page that has been statically generated, you can do so by setting revalidate in the page's getStaticProps function. If you're using next/image, there are also specific caching rules for the default Image Optimization loader.

Note: When running your application locally with next dev, your headers are overwritten to prevent caching locally.

Cache-Control: no-cache, no-store, max-age=0, must-revalidate

You can also use caching headers inside getServerSideProps and API Routes for dynamic responses. For example, using stale-while-revalidate.

// This value is considered fresh for ten seconds (s-maxage=10).
// If a request is repeated within the next 10 seconds, the previously
// cached value will still be fresh. If the request is repeated before 59 seconds,
// the cached value will be stale but still render (stale-while-revalidate=59).
//
// In the background, a revalidation request will be made to populate the cache
// with a fresh value. If you refresh the page, you will see the new value.
export async function getServerSideProps({ req, res }) {
  res.setHeader(
    'Cache-Control',
    'public, s-maxage=10, stale-while-revalidate=59'
  )

  return {
    props: {},
  }
}

Note: Your deployment provider must support edge caching for dynamic responses. If you are self-hosting, you will need to add this logic to the edge yourself using a key/value store. If you are using Vercel, edge caching works without configuration.

To reduce the amount of JavaScript sent to the browser, you can use the following tools to understand what is included inside each JavaScript bundle:

• Import Cost – Display the size of the imported package inside VSCode.
• Package Phobia – Find the cost of adding a new dev dependency to your project.
• Bundle Phobia - Analyze how much a dependency can increase bundle sizes.
• Webpack Bundle Analyzer – Visualize size of webpack output files with an interactive, zoomable treemap.

Each file inside your pages/ directory will automatically be code split into its own JavaScript bundle during next build. You can also use Dynamic Imports to lazy-load components and libraries. For example, you might want to defer loading your modal code until a user clicks the open button.

Since Next.js runs on both the client and server, there are multiple forms of logging supported:

• console.log in the browser
• stdout on the server

If you want a structured logging package, we recommend Pino. If you're using Vercel, there are pre-built logging integrations compatible with Next.js.

When an unhandled exception occurs, you can control the experience for your users with the 500 page. We recommend customizing this to your brand instead of the default Next.js theme.

You can also log and track exceptions with a tool like Sentry. This example shows how to catch & report errors on both the client and server-side, using the Sentry SDK for Next.js. There's also a Sentry integration for Vercel.

For more information on what to do next, we recommend the following sections: