Written by Krisztián Stark
Key takeaways
- A deep link takes the user to a specific place inside an app, such as a product, a level, or a sign-up screen.
- Android App Links and iOS Universal Links are verified web links: they open the app when it is installed and the website when it is not.
- A deferred deep link remembers the destination through the app store install, so a new user still lands on the right screen.
What is a deep link?
A deep link is a link that opens a specific screen inside a mobile app, rather than just launching the app or sending the user to a web page. Tapping a deep link for a shoe can open that exact product in the shop’s app; a link in a game ad can open the event screen instead of the main menu.
For marketing, deep links remove steps. Every extra screen between the ad and the goal loses users, so sending people straight to what they clicked on usually raises conversion.
Types of deep links
| Type | Looks like | If the app is installed | If it is not |
|---|---|---|---|
| Custom URL scheme | myapp://level/12 | Opens the app, if no other app claims the same scheme | Does nothing or shows an error |
| Android App Links | https://example.com/level/12 | Opens the app directly, without asking | Opens the website |
| iOS Universal Links | https://example.com/level/12 | Opens the app directly | Opens the website in the browser |
| Deferred deep link | Usually a tracking or link-service URL | Opens the app at the destination | Sends the user to the store, then opens the destination after install |
Custom URL schemes
The oldest method: an app registers a scheme such as myapp:// and the system sends matching links to it. Apple’s documentation calls this an acceptable form of deep linking but strongly recommends universal links instead, and warns that if several apps register the same scheme, which app opens is undefined. Android’s standard deep links, which can use custom schemes or web addresses, may show a dialog asking the user which app should open the link.
Android App Links
According to Android’s developer documentation, App Links are verified web links supported on Android 6 and later, on devices with Google services. The app declares its web addresses in its manifest with autoVerify turned on, and the website publishes a file called assetlinks.json in its /.well-known/ folder listing the apps allowed to handle its links. Once Android verifies that two-way link, matching URLs open the app directly, with no app chooser. From Android 15, Dynamic App Links let developers change which paths open the app from the assetlinks.json file, without releasing an app update.
iOS Universal Links
Apple’s Universal Links work the same way. The app adds the Associated Domains entitlement, and the website hosts an apple-app-site-association file in its .well-known directory, served over https with a valid certificate and no redirects. When the app is installed, links to that domain open it; when it is not, the same URL opens the website. One detail catches many teams: if a user is already browsing your site in Safari and taps a universal link to the same domain, iOS keeps them in Safari.
What is a deferred deep link?
A standard deep link only works when the app is already installed. A deferred deep link remembers where the user wanted to go, sends them to the app store, and opens that destination on the first launch after the install. That is what lets an ad for a specific product or referral code still work for a brand new user.
The platforms do not fully handle this on their own. On Android, the Google Play Install Referrer API can pass campaign parameters through the install. Beyond that, deferred deep linking is usually provided by mobile measurement partners and link services, which match the first launch to the earlier click. What is an MMP? covers how that matching works.
If you still use Firebase Dynamic Links, note that Google shut the service down on August 25, 2025. Its FAQ says links clicked after the shutdown return an HTTP 404 response, so old campaign links built on it need replacing.
How campaigns use deep links
- Product and content ads. Send users to the exact item in the ad, not the home screen.
- Onboarding for new users. A deferred link can open a welcome screen that matches the ad they clicked, or apply a promo code automatically.
- Re-engagement. Bring existing users back to a new level or a cart they left. On iOS 18 and later, Apple’s AdAttributionKit can open a registered universal link when an ad brings back a user who already has the app.
- Referrals. Carry the inviter’s code through the install so both users get their reward.
- Tracking. Add campaign parameters to the link so you can see which source sent each user. See UTM parameters explained and click ID and sub ID.
Illustrative funnel: home screen vs deep link
An ad promotes a free spin event in a game. With a plain store link, 1,000 new players open the app on the home screen and 200 find the event. With a deferred deep link, the same 1,000 land on the event screen and 550 take part. The rates are invented, but the direction is typical: each screen you remove keeps more of the users you paid for.
Common deep link mistakes
- Not testing the not-installed path, so new users from an ad land on a broken page.
- Serving the association file with a redirect or the wrong content, so verification fails silently.
- Dropping campaign parameters during redirects, which breaks attribution.
Deep links and multi-step offers on Sharklio
On Sharklio, a multi-step offer campaign pays for steps your own server confirms by postback, such as the install, the tutorial, and a later level, up to 15 paid steps. A deep link that takes new users straight to the first step usually means more of them reach the steps you pay for. Every campaign is reviewed by staff before it goes live, and you can target by country, device type, and OS, so iOS and Android links can run as separate campaigns. See task vs offer campaigns or Sharklio for advertisers.
Related terms: attribution in mobile marketing and CTR vs CVR.
Frequently asked questions
What is the difference between a deep link and a deferred deep link?
A deep link opens a screen in an app that is already installed. A deferred deep link also works for new users: it keeps the destination through the store install and opens it on the first launch.
What is the difference between App Links and Universal Links?
They are the Android and iOS versions of the same idea: verified web links that open your app when it is installed and your website when it is not.
Do I need an MMP for deep linking?
Not for standard App Links and Universal Links, which you can set up yourself. Deferred deep linking usually relies on an MMP or a link service.
What happened to Firebase Dynamic Links?
Google shut the service down on August 25, 2025. Links built on it return an error, so apps need another deep linking setup.
