What is deep linking?

Deep linking is the practice of using a URL to open a specific screen inside a mobile app instead of its home screen. On iOS this is done with Universal Links, on Android with App Links. Both require the app’s owner to publish a small verification file on the domain the links use, which is the part most teams would rather not build and host themselves.

The vocabulary, briefly

Deep link

A deep link is a URL that opens a specific screen inside a mobile app rather than the app’s home screen. A link to a single product, article or conversation is a deep link; a link that only launches the app is not.

Universal Link (iOS)

A Universal Link is Apple’s mechanism for associating a standard https URL with an iOS app. When the app is installed, iOS opens it directly; when it is not, the same URL opens in Safari. It requires an Apple App Site Association (AASA) file served from the domain.

App Link (Android)

An Android App Link is Google’s equivalent: a verified https URL that opens the app directly. Verification requires an assetlinks.json file served from the domain, listing the app’s package name and signing certificate fingerprint.

Custom URL scheme

A custom scheme such as myapp:// is the older approach to deep linking. It works only when the app is already installed, offers no fallback in a browser, and can be claimed by more than one app, which is why Universal Links and App Links replaced it for most uses.

Deferred deep linking

Deferred deep linking preserves the intended destination across an app install. A user taps a link without the app, installs it from the store, and on first launch lands on the screen the link pointed to rather than the default home screen.

Fallback URL

A fallback URL is where a deep link sends someone when the app cannot be opened — usually the App Store or Google Play listing, or a web version of the same content.

Why teams outsource it

Deep linking looks simple until you implement it. You need a domain, a correctly formed AASA file and assetlinks.json served at the right paths with the right content type, a certificate that renews, short-code generation and storage, social metadata for link previews, click tracking, and a fallback path for every platform that is not iOS or Android. Deep Blue Links provides all of it as a service, which is what we mean by not having to stand up your own web app.