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Add a web app manifest | Articles

A web app manifest is a JSON file that tells the browser how your Progressive Web App (PWA) should behave when installed on the user's desktop or mobile device. At minimum, a typical manifest file includes:

• The app's name
• The icons the app should use
• The URL that should be opened when the app launches

The manifest file can have any name, but it's commonly named manifest.json and served from the root (your website's top-level directory). The specification suggests the extension should be .webmanifest, but you might want to use JSON files to make your manifests clearer to read.

A typical manifest looks like this:

{
  "short_name": "Weather",
  "name": "Weather: Do I need an umbrella?",
  "icons": [
    {
      "src": "/images/icons-vector.svg",
      "type": "image/svg+xml",
      "sizes": "512x512"
    },
    {
      "src": "/images/icons-192.png",
      "type": "image/png",
      "sizes": "192x192"
    },
    {
      "src": "/images/icons-512.png",
      "type": "image/png",
      "sizes": "512x512"
    }
  ],
  "id": "/?source=pwa",
  "start_url": "/?source=pwa",
  "background_color": "#3367D6",
  "display": "standalone",
  "scope": "/",
  "theme_color": "#3367D6",
  "shortcuts": [
    {
      "name": "How's the weather today?",
      "short_name": "Today",
      "description": "View weather information for today",
      "url": "/today?source=pwa",
      "icons": [{ "src": "/images/today.png", "sizes": "192x192" }]
    },
    {
      "name": "How's the weather tomorrow?",
      "short_name": "Tomorrow",
      "description": "View weather information for tomorrow",
      "url": "/tomorrow?source=pwa",
      "icons": [{ "src": "/images/tomorrow.png", "sizes": "192x192" }]
    }
  ],
  "description": "Weather forecast information",
  "screenshots": [
    {
      "src": "/images/screenshot1.png",
      "type": "image/png",
      "sizes": "540x720",
      "form_factor": "narrow"
    },
    {
      "src": "/images/screenshot2.jpg",
      "type": "image/jpg",
      "sizes": "720x540",
      "form_factor": "wide"
    }
  ]
}

You must provide at least one of short_name or name in your manifest. If you provide both, name is used when the app is installed, and short_name is used on the user's home screen, launcher, or other places where space is limited.

When a user installs your PWA, you can define a set of icons for the browser to use on the home screen, app launcher, task switcher, splash screen, and in other places.

The icons property is an array of image objects. Each object must include the src, a sizes property, and the type of image. To use maskable icons, sometimes referred to as adaptive icons on Android, add "purpose": "any maskable" to the icon property.

For Chromium, you must provide at least a 192x192 pixel icon and a 512x512 pixel icon. If only those two icon sizes are provided, Chrome automatically scales the icons to fit the device. If you'd prefer to scale your own icons, and adjust them for pixel-perfection, provide icons in increments of 48dp.

The id property lets you explicitly define the identifier used for your application. Adding the id property to the manifest removes the dependency on the start_url or the location of the manifest, and makes it possible to update them in the future. For more information, see Uniquely identifying PWAs with the web app manifest ID property.

The start_url is a required property. It tells the browser where your app should start when it launches, and prevents the app from starting on whatever page the user was on when they added your app to their home screen.

Your start_url should direct the user straight into your app, not a product landing page. Think about what the user will want to do immediately after they open your app, and place them there.

The background_color property is used on the splash screen when the application launches on mobile for the first time.

You can customize what browser UI is shown when your app is launched. For example, you can hide the address bar and browser user interface elements. Games can even be made to launch in full screen. The display property takes one of the following values:

To choose how your web app is displayed, set a display mode in its manifest as explained earlier. Browsers aren't required to support all display modes, but they are required to support the spec-defined fallback chain ("fullscreen" → "standalone" → "minimal-ui" → "browser"). If they don't support a given mode, they fall back to the next display mode in the chain. In rare cases, these fallbacks can cause problems. For example, a developer can't request "minimal-ui" without being forced back into the "browser" display mode when "minimal-ui" is not supported. The current behavior also makes it impossible to introduce new display modes in a backwards-compatible way, because they don't have a place in the fallback chain.

You can set your own fallback sequence using the display_override property, which the browser considers before the display property. Its value is a sequence of strings that are considered in the listed order, and the first supported display mode is applied. If none are supported, the browser falls back to evaluating the display field. If there's no display field, the browser ignores display_override.

The following is an example of how to use display_override. The details of "window-control-overlay" are out of scope for this page.

{
  "display_override": ["window-control-overlay", "minimal-ui"],
  "display": "standalone",
}

When loading this app, the browser tries to use "window-control-overlay" first. If that's unavailable, it falls back to "minimal-ui", and then to "standalone" from the display property. If none of these are available, the browser then returns to the standard fallback chain.

The scope of your app is the set of URLs that the browser considers part of your app. scope controls the URL structure that includes all entry and exit points to the app, and the browser uses it to determine when the user has left the app.

A few other notes on scope:

• If you don't include a scope in your manifest, then the default implied scope is the start URL, but with its filename, query, and fragment removed.
• The scope attribute can be a relative path (../), or any higher level path (/) that would allow for an increase in coverage of navigations in your web app.
• The start_url must be in the scope.
• The start_url is relative to the path defined in the scope attribute.
• A start_url starting with / will always be the root of the origin.

The theme_color sets the color of the tool bar, and can be reflected in the app's preview in task switchers. The theme_color should match the meta theme color specified in your document head.

You can adjust theme_color in a media query using the media attribute of the meta theme color element. For example, you can define one color for light mode and another one for dark mode in this way. However, you can't define these preferences in your manifest. For more information, see the w3c/manifest#975 GitHub issue.

<meta name="theme-color" media="(prefers-color-scheme: light)" content="white">
<meta name="theme-color" media="(prefers-color-scheme: dark)"  content="black">

The shortcuts property is an array of app shortcut objects that provide quick access to key tasks within your app. Each member is a dictionary that contains at least a name and a url.

The description property describes the purpose of your app.

In Chrome, the maximum description length is 300 characters on all platforms. If the description is longer than that, the browser truncates it with an ellipsis character. On Android, the description must also use a maximum of seven lines of text.

The screenshots property is an array of image objects representing your app in common usage scenarios. Each object must include the src, a sizes property, and the type of image. The form_factor property is optional. You can set it either to "wide" for screenshots applicable to wide screens only or "narrow" for only narrow screenshots.

In Chrome, the image must meet the following criteria:

• Width and height must be at least 320 px and at most 3840 px.
• The maximum dimension can't be more than 2.3 times the length of the minimum dimension.
• All screenshots matching the appropriate form factor must have the same aspect ratio.
  • From Chrome 109, only screenshots with the form_factor set to "wide" are displayed on desktop.
• From Chrome 109, screenshots with the form_factor set to "wide" are ignored on Android. Screenshots without form_factor are still displayed for backwards compatibility.

Chrome on desktop displays at least one and at most eight screenshots that meet these criteria. The rest are ignored.

Chrome on Android displays at least one and at most five screenshots that meet these criteria. The rest are ignored.

After creating the manifest, add a <link> tag to all the pages of your Progressive Web App. For example:

<link rel="manifest" href="/manifest.json">

To verify your manifest is set up correctly, use the Manifest pane in the Application panel of Chrome DevTools.

This pane provides a human-readable version of many of your manifest's properties, and lets you verify that all of the images are loading properly.

When your app first launches on mobile, it can take a moment for the browser to start and the initial content to begin rendering. Instead of showing a white screen that might make the user think the app isn't working, the browser shows a splash screen until the first paint.

Chrome automatically creates the splash screen from the name, background_color, and icons specified in your manifest. To create a smooth transition from the splash screen to the app, make you background_color the same color as the load page.

Chrome chooses the icon that most closely matches the device resolution for the splash screens. Providing 192px and 512px icons is sufficient for most cases, but you can provide additional icons for a better match.

To learn about other properties you can add to your web app manifest, refer to the MDN Web App Manifest documentation.

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