This example consists of two Next.js applications that are served on the same domain to look and feel like a single application.

The first application is the "host application". All requests go to this application first, and then the request is rewritten to proceed to the "child application".

Next.js only allows one basePath on an application. basePath allows Next.js to automatically prefix all paths with the value to make the paths unique. This is used in multi-zone applications to carve out the URL space from the host application paths. However, all paths in an application must have this path as a prefix, which isn't always true in practice. For example:

• /, /help, /contact are served by the host application.
• /docs, /guides, /blog are served by the child application.

The paths for the child application don't share a common path prefix.

To work around this, you can use Next.js rewrites to hide the basePath.

  async rewrites() {
    return [
      {
        source: '/child-app/:path*',
        destination: 'http://localhost:3001/child-app/:path*',
      },
      {
        source: '/docs/:path*',
        destination: 'http://localhost:3001/child-app/docs/:path*',
      },
      {
        source: '/guides/:path*',
        destination: 'http://localhost:3001/child-app/guides/:path*',
      },
    ];
  }

When the user visits /guides, they will never see the /child-app/guides path but it exists behind the scenes to route the request to the correct application.

Since multi-zone applications are separate Next.js applications, they had a hard nav when you navigate between pages in the different applications. This may result in extra latency and slower feel due to having to change documents and load different resources from scratch.

To help, you can use the view transition API with cross document support to have an animation that makes it look like pages are part of the same application.

This is a new spec. It's only implemented in Chrome right now, behind a flag (intended to launch in Chrome 127). Gecko has expressed positive interest in the API but Webkit has not given a signal whether they intend to support this API.

In Chrome, you can opt in to this API by navigating to chrome://flags and then turning on view-transition-on-navigation.

See https://github.com/WICG/view-transitions/blob/main/explainer.md#cross-document-same-origin-transitions for more details.