Universal links vs. deep links: What's the difference?

Deep linking, known for its conversion-boosting abilities, is an essential component of mobile marketing, given the ongoing challenges of complex user journeys that both app users and developers face. Among this conversation, the term ‘universal links’ appears. Let’s look at what differentiates them from the broader ‘deep links.’

Simply put, universal links are Apple’s way of linking to a page within an app. Of course, in practice there are some nuances to how this works.

When a user taps a universal link from their smartphone, one of two things will happen:

1. If the app is installed, it will launch and the user be sent to the relevant content.
2. If the app is not installed, the page is opened within a web browser like a traditional URL.

Universal links are available in iOS version 9 and above, and work even when the app isn’t installed on a user’s device as described above. The ability for these URLs to send the user to either your app or your website is where the ‘universal’ concept comes from.

This journey was built by Apple to follow through on the user’s assumed intent. While technically this is known as the user’s “entitlement” (more on the complexities of this in a minute), it essentially intends to reflect that if a user has the app installed, they would generally like to open your link in the associated app, while if they do not, they would like to open the link in your mobile website. In practice, however, this gets a little messy–see limitations below.

To activate universal links, a developer will first provide a map between the website and app. In essence, this step matches a set of web pages to their corresponding location in-app. Technically, Apple refers to this as “supporting associated domains”. The associated domain file is added to your website under a path determined by Apple. If you’re leveraging universal links with Adjust, this step is taken care of by us, as we host the file on your behalf.

When this is done, you’ll need to update your app delegate to respond to the updates in the NSUserActivity object, which is triggered when a user opens one of the associated domains. Then, once activated, when a user has installed the app, and taps a universal link, iOS will automatically redirect the user to the app. There are, however, a couple of exceptions to this rule. The page will open in Safari, rather than your app, when:

1. A user does not have your app installed (or does not have the correct version installed).
2. A user is browsing your website in Safari and taps a universal link in the same domain. Think, you’re browsing the mobile website of Reddit, you tap a universal link to a specific subreddit, and instead of being directed to open this subreddit in the app, you continue your journey in the mobile browser.

It’s not possible to track clicks from these links, given that the app opens immediately from the universal link and a redirect through a webpage to count the click is not possible.

Adjust allows you to create deep links without extra fuss. Whether you want to create a deep link URL for a campaign you are running with a partner or for your owned and earned traffic (i.e. a social media post) you can generate a deep link within Campaign Lab in the Partner or Custom Links sections. Simply copy and paste the generated link into whichever campaign you’ve set–Adjust deep links can work for both Android and iOS, greatly reducing the hassle of implementing deep links yourself.