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Deep Linking
October 20, 2026 A deep link is a link that takes users straight to a specific screen inside an app, such as a product page or the cart, instead of just opening the app’s home screen. Deep linking is the practice of setting up these links and using them in ads, email, SMS, QR codes and push notifications.
What is a deep link and why do you need one?
A user taps an ad for a pair of shoes on TikTok. Without a deep link, the app opens on its home screen and they have to hunt for the shoes again. Every extra step is one more chance for them to give up. With a deep link, they land on the right product page with the discount code already applied.
Deep links carry campaign parameters, so the measurement system knows which ad led to each app open. Re-engagement campaigns that bring past users back into the app all depend on this.
Types of deep links
| Type | Link format | If the app is not installed | Verification |
|---|---|---|---|
| URI scheme | appname://product/123 | Shows an error or does nothing | None |
| Universal Links (iOS) | https://yourdomain.com/product/123 | Opens the web page in the browser | apple-app-site-association file on the website |
| App Links (Android) | https://yourdomain.com/product/123 | Opens the web page in the browser | assetlinks.json file on the website |
| Deferred deep link | A measurement platform’s link | Sends the user to the store, then opens the right content after install | Through the measurement SDK |
Universal Links are ordinary http or https links. When a user taps one, iOS opens the app directly without going through the browser. If the app is not installed, the link opens in the default browser. When the app is installed, the system checks a file on the web server to confirm that the website allows the app to open its links (Apple Developer Documentation).
Android App Links are deep links whose domain ownership has been verified through a Digital Asset Links file. A verified link opens the app directly, with no dialog asking the user which app to use. App Links work on Android 6 and later, on devices with Google services. Android 15 added Dynamic App Links, which let you change link-matching rules without shipping a new version of the app (Android Developers, updated October 2026).
Deferred deep links solve the problem for people who do not have the app yet. They tap the link, go to the App Store or Google Play, install, open the app for the first time and still land on the right product page. On Android, Google Play offers the Install Referrer API so the app can retrieve this referral content securely (Android Developers, July 2025). In practice, most apps rely on an MMP SDK to handle both iOS and Android.
Firebase Dynamic Links has shut down
Firebase Dynamic Links (page.link URLs) used to be a free way to build deferred deep links. Google turned the service off on August 25, 2025. Every link stopped working, including links on custom domains, and new links can no longer be created (Firebase, Dynamic Links Deprecation FAQ). Any QR code on packaging, flyers or old emails that still points to page.link is now broken. Firebase recommends moving to App Links and Universal Links.
Example (hypothetical)
A fashion app runs an ad offering 30% off its fall collection. The link in the ad points to https://yourdomain.com/fall-collection?code=FALL30.
- Users who already have the app: Universal Links or App Links open the collection page directly, with the code FALL30 filled in automatically.
- Users who do not have the app: a deferred deep link sends them to the store, and after installing they still land on that page.
- Devices that cannot open the app: the link falls back to the web page at the same address, so the customer can still buy on the web.
Deep links vs. deferred deep links
A standard deep link usually works only when the app is already on the device. A deferred deep link adds a step that “remembers” the link through the install. Campaigns aimed at new users need deferred deep links. Campaigns retargeting existing users only need deep links.
Frequently asked questions
Why does a Universal Link open the website instead of the app?
According to Apple, when a user is browsing a website in Safari and taps a link on the same domain, iOS keeps them in Safari. Only a link from a different domain opens the app.
Do you need an MMP for deep linking?
Not for basic deep links. For deferred deep links and install source measurement, you almost always do.
If you need to audit the links in your app’s ads, emails and QR codes, or check your measurement after replacing Firebase Dynamic Links, Adtek’s measurement team can help. Reach us through our contact page.
