Add or generate a manifest.(json|webmanifest) file that matches the Web Manifest Specification in the root of app directory to provide information about your web application for the browser.

Static Manifest file

{
  "name": "My Next.js Application",
  "short_name": "Next.js App",
  "description": "An application built with Next.js",
  "start_url": "/"
  // ...
}

Generate a Manifest file

Add a manifest.js or manifest.ts file that returns a Manifest object.

Good to know: manifest.js is a special Route Handlers that is cached by default unless it uses a Request-time API or dynamic config option.

import type { MetadataRoute } from 'next'

export default function manifest(): MetadataRoute.Manifest {
  return {
    name: 'Next.js App',
    short_name: 'Next.js App',
    description: 'Next.js App',
    start_url: '/',
    display: 'standalone',
    background_color: '#fff',
    theme_color: '#fff',
    icons: [
      {
        src: '/favicon.ico',
        sizes: 'any',
        type: 'image/x-icon',
      },
    ],
  }
}

export default function manifest() {
  return {
    name: 'Next.js App',
    short_name: 'Next.js App',
    description: 'Next.js App',
    start_url: '/',
    display: 'standalone',
    background_color: '#fff',
    theme_color: '#fff',
    icons: [
      {
        src: '/favicon.ico',
        sizes: 'any',
        type: 'image/x-icon',
      },
    ],
  }
}

Manifest Object

The manifest object contains an extensive list of options that may be updated due to new web standards. For information on all the current options, refer to the MetadataRoute.Manifest type in your code editor if using TypeScript or see the MDN docs.

Source: docs/01-app/03-api-reference/03-file-conventions/01-metadata/manifest.mdx