Deep links send users to a specific place inside an app instead of the home screen. On iOS, Universal Links use your website domain and an apple-app-site-association file; on Android, App Links use a verified assetlinks.json file. Deferred deep links remember the destination through an install, so new users land on the right content after downloading. Firebase Dynamic Links shut down in 2025, so teams now use MMP or dedicated linking providers, or build their own.
Why deep links matter
Without deep links, a user who taps a link to a product, article, or invite lands on the app's home screen or the store page, and must find the content again. Many give up. Deep links remove that friction, improving conversion for ads, emails, referrals, influencer campaigns, QR codes, and web-to-app flows.
Deep links also improve attribution, because the link can carry campaign information through to the app. Our guides to referral programs and influencer marketing rely on deep links to deliver personalized experiences.
Types of deep links
Custom URL schemes, such as myapp://product/123, are the oldest method. They are easy to set up but not unique, can be claimed by other apps, and fail with an error if the app is not installed. Modern apps use them only as a fallback.
Universal Links on iOS and App Links on Android use standard web URLs on your own domain. If the app is installed, the link opens the app at the right place; if not, it opens the web page, which can redirect to the store. Because they rely on domain verification, they are secure and reliable.
Setting up Universal Links and App Links
For Universal Links, host an apple-app-site-association file on your domain listing your app identifiers and the paths the app handles, and add the Associated Domains entitlement to your app. For Android App Links, host an assetlinks.json file on your domain with your app's package name and signing certificate fingerprint, and declare intent filters with autoVerify in your manifest.
Test on real devices after every change to domains, app identifiers, or signing keys. A silent failure falls back to the web, which looks like the link works but loses the in-app experience. Our web-to-app SEO guide covers related website setup.
Deferred deep links
Deferred deep links handle users who do not have the app installed. The link sends them to the store, and after they install and open the app, it routes them to the original destination. This is essential for campaigns that target new users, such as referrals and ads.
On Android, the Google Play Install Referrer API can pass referral information through the install. On iOS, deferred linking is more constrained by privacy rules, and providers use privacy-compliant matching methods. Most teams use a mobile measurement partner or linking provider for deferred deep links; see our MMP comparison.
After Firebase Dynamic Links
Firebase Dynamic Links, a popular free solution, was shut down by Google in August 2025. Apps that relied on it needed to migrate to alternatives: MMP-provided links, dedicated linking providers such as Branch, or self-built solutions using Universal Links, App Links, and the Install Referrer API.
When migrating, inventory every place links appear, including emails, QR codes, printed materials, and partner sites, and set up redirects where possible. Test deferred flows end to end, and update analytics so campaign tracking continues.
Use cases across the funnel
Paid ads can deep link to specific products or content shown in the creative, improving conversion. Email and push campaigns can link to personalized screens. Referral links can open a welcome screen naming the inviter. QR codes in stores or events can open relevant features.
Web-to-app flows benefit too: a user reading an article on your site can open it in the app with one tap. On iOS, Smart App Banners can prompt Safari users to open or install the app. Our app landing page best practices guide covers web flows.
Deep links and the store page
When users without the app tap a deep link, they see your store page before installing. Matching the store page to the link context improves conversion: custom product pages on iOS and custom store listings on Google Play can reflect campaign themes.
After install, the deferred deep link should deliver the promised content immediately. A user who tapped a link for a specific recipe expects to see that recipe, not a generic onboarding flow.
Common deep linking mistakes
Broken association files after domain or signing changes are the most common issue, causing links to fall back to the web silently. Another is relying only on custom URL schemes, which fail when the app is not installed. Many teams also forget deferred deep linking, losing context for new users.
After the Firebase Dynamic Links shutdown, some apps still have old links in circulation that no longer work. Finally, failing to test on multiple devices, OS versions, and apps such as email clients and social apps, which sometimes open links in in-app browsers, leads to unexpected failures.
A worked example: a recipe app's link strategy
A recipe app shares links to recipes on social media and in emails, but links open the home screen, and new users land on a generic store page. The team sets up Universal Links and App Links on its domain, and uses a linking provider for deferred deep links.
Now existing users open the exact recipe, and new users install and land on that recipe after a short welcome. Conversion from shared links rises, and attribution shows which recipes drive installs. The team uses those insights to choose recipes for screenshots and ads.
How to do it, step by step
- Map link destinationsList the screens and content you want links to open, and where links will appear.
- Set up Universal Links and App LinksHost association files on your domain and configure entitlements and intent filters.
- Add deferred deep linkingUse an MMP, linking provider, or the Install Referrer API to preserve destinations through install.
- Migrate legacy linksReplace Firebase Dynamic Links and custom schemes, with redirects for old links.
- Test across devices and appsVerify links on real devices, OS versions, and apps with in-app browsers.
Before and after examples
Illustrative examples written for a generic app in this category, not client results. Swap in your own product, audience, and data.
myapp://recipe/42 shared in emails.
https://example.com/recipe/42 as a Universal Link and App Link.
Why it works: Web URLs work whether or not the app is installed.
Install, then land on the home screen.
Install, then land on the shared recipe after a short welcome.
Why it works: Deferred deep links preserve intent and improve activation.
Leave old Firebase Dynamic Links in place.
Replace them with new links and redirect where possible.
Why it works: Firebase Dynamic Links no longer work after the 2025 shutdown.
Action plan
- Use Universal Links and App Links
- Add deferred deep linking for new users
- Replace Firebase Dynamic Links
- Match store pages to link context
- Deliver promised content after install
- Test after every domain or signing change
Metrics to monitor
- Deep link success versus fallback rate
- Install conversion from links
- Activation of deep-linked new users
- Installs by link source
- Broken link reports
Record the baseline, release date, audience, markets, and external changes before interpreting movement. Rankings and conversion are useful signals, but a decision is stronger when activation, retention, and business value confirm that the page attracted the right users.
Frequently asked questions
What is a deferred deep link?
A link that remembers its destination through an app install, so new users land on the intended content after downloading and opening the app.
What replaced Firebase Dynamic Links?
Google shut down Firebase Dynamic Links in August 2025. Teams now use MMP links, dedicated linking providers, or build their own with Universal Links, App Links, and the Install Referrer API.
What is the difference between Universal Links and URL schemes?
Universal Links use verified web URLs and fall back to the website if the app is not installed; URL schemes are app-specific and fail if the app is missing.
Do deep links help app store optimization?
Indirectly. They improve conversion and activation from campaigns and web traffic, and support web-to-app discovery.
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