PMG Digital Made for Humans

An In-Depth Guide to Deep Linking and App Indexing

8 MINUTE READ | July 6, 2016

An In-Depth Guide to Deep Linking and App Indexing

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Kara Eccleston

Kara Eccleston has written this article. More details coming soon.

app deep links and indexing

Upon their inception, Google’s mission has been to organize the world wide web. But then apps came along and threw them a curve ball. Because apps do not have the same explicit path structure as websites and live natively on a user’s device, Google cannot crawl app content unless deep links exist. Although deep links have been available for almost as long as apps have, the explosion of mobile commerce has forced retailers to pay more attention to the power of deep linking since conversion rates on mobile apps exceeds that of mobile web.

Deep linking connects a unique URL to a defined action in a mobile app versus just launching the app’s home screen. By doing so, users can be sent to relevant content inside the app. To enable deeplinking, deep links must contain these basic structural elements:

  • A URL with a unique scheme name. This name must be unique so most applications tend to stick with their brand name. This is sometimes done in the form of reverse domain name notation (e.g. com.pmg).

  • To perform certain actions and route people to particular app screens, routing parameters must be utilized using paths and query strings (e.g. schemename://path?query_string). The query string is only necessary if you need to pass a specific parameter such as a product ID (e.g. a retail app needs to point people to a product page within the app).

What a Web Link looks like: /blog/my-blog-postWhat an app deep link looks like: com.pmg://blog/seo/post124

app indexing gif

Social Media (Twitter) to App (Spotify)

Deep links allow the the user to be taken directly to app content in the following interactions:

  • Website to App

  • App to App

  • Social Media to App

  • Search Result to App (using app indexing)

  • Mobile Phone Search to App (for example, Apple Spotlight Search)

  • Ad to App

  • E-mail to App

  • SMS to App

Universal links allows iOS users to tap a link to your website and be redirected to your installed app without going through Safari. Before iOS 9 was launched, deep links that utilized URI schemes would result in an ugly “Cannot Open Page” error when clicked if the user did not have the app installed.

deep link error iOS


To avoid this, developers would then have to manually add some JavaScript to the web page to redirect the user to the App Store if the app was not installed on the device. If the app was installed, the user would be prompted to open the app or to cancel and continue in the browser. But after an update in Safari, the JavaScript redirect to the App Store would execute before the user had a chance to click “Open App”. All in all, it made for a poor user experience. Therefore, Apple introduced Universal Links as a solution to this problem. Universal links allow routing to occur within the operating system as opposed to using JavaScript.

Unfortunately, universal links do not work everywhere so it is important to still use URI scheme deeplinks.

universal link support


Adding support for universal links involves three key steps:

  1. Associate your app with your website by creating a filed that contains JSON data about the URLs your app can handle called apple-app-site-association (do not append .json to the filename).

  2. Upload the file to your HTTPS web server at the root of the server. SSL certificiation for the domain you plan on hosting the universal links on is required for universal links to work. They must also be accessible without any redirects.

  3. Prepare your app to handle universal links by adding an entitlement that specifies the domains your app supports and update your app delegate so that it responds appropriately to the NSUserActivity object.

Full documentation can be found here. For more detailed steps implementing app indexing can be found here for Android and here for iOS. To enable app content indexing on iOS devices, check out Apple’s Core Spotlight APIs. This allows content from your app to show up in iOS Spotlight Search, Siri, and Safari. 

spotlight search

App Links aren’t actually links at all. Instead, they are essentially open graph tags for app content. Just like there is an Open Graph Protocol, there is an App Links Protocol. App Links are supported by Facebook, Pinterest, and Spotify. This is how they work:

  1. App links are added to existing web content by adding metadata to describe the content (for example: /bog/my-post). If web content does not exist for the app or if the web content cannot be annotated, the meta data can be hosted through a Facebook-provided API.

  2. When someone shares a story, Facebook (or another supported platform) looks up the URL to see if it supports App Links.

  3. If the person has the app installed, Facebook launches the app with information that your app can use to directly load the content. If the app is not installed, Facebook launches the web-equivalent of the app content.

Similar to App Links, Twitter has their own protocol called App Cards. By adding meta data to the section of the site, Twitter can fetch information about your app such as name, description and icon, and also highlight attributes such as the rating and the price. Depending on the configuration, users can either be taken directly to the app content (if on mobile) or be directed to the app store listing in Google Play or App Store.

If the app does not have a website, simply sharing the App Store or Google Play Store URL will allow Twitter to populate name, star ratings, price, and description within the card.

  • Direct social media traffic to your app

  • Increase ad ROI by sending users directly into an in-app product page

  • Enable partnerships with other apps (ex: Google Maps & Uber)

  • Ranking boost on mobile searches if app indexing is enabled

Crawling and indexing in-app content used to be impossible without deep links limiting app discovery to the app store. App Indexing allows Google to crawl your app content as if it were a website. This allows people to click from listings in Google’s search results into apps on their Android and iOS smartphones or tablets. However, for app content to be be indexed, the app content must have  corresponding web content.

Google Search (mobile web) to Pinterest (in app)

The steps to enabling app indexing vary between iOS and Android but can be generally broken down into these three basic steps:

  1. Associate your website with your app. To do this, your app needs to be able to parse and handle HTTP URLs that correspond with links to your website.

  2. Add the SDK for iOS or the App Indexing API for Android.

  3. Test your implementation by using a testing tool such as Search Preview Tool to verify that the App Indexing implementation is working correctly.

Yes. It was announced at Google IO’15 that Google is starting to index app-only content and will show relevant app-only results alongside web results. However, as of now, Google is only doing this by request so app developers have to fill out and submit an Expression of Interest Form. Submitting a form does not guarantee that Google will index the app content and as of now it appears that indexing app-only content is only available for Android apps.

  • Aids in discoverability by surfacing your app in Google search results.

  • Conversion rates tend to be higher for apps versus websites.

  • Users can land on screens within the app, not just the app home screen.

  • A brand with an app gets a ranking boost over a regular site.

  • Google Now on Tap can send searchers into your app from another app.

  • App Indexing associates your app and website, so your app install card displays next to your website card.

  • App pages can appear as autocompletions in the Google app with the Android App Indexing API.

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Deep links allow connections to made between the mobile web and mobile apps. By clicking on a deep link, a user is sent straight to the specified app content verses just being sent to the home screen. When deep links are present, app indexing can be enabled. App indexing allows app content to be displayed in Google search results. Utilizing deep links and app indexing can increase app engagement and improve conversion rates.

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