Deep link & Universal link

Deep link

• In the broadest sense, a "deep link" is any link that sends a user directly to specific content inside an app, rather than just launching the app's home screen.

• Format: myapp://path/to/content

• How it works: You register a unique "scheme" (like twitter:// or spotify://) in your app’s code. When a user clicks a link with that scheme, the phone looks for an app claiming that name and opens it.

  • The Problem:

    • If the app is installed: It works great.

    • If the app is NOT installed: The user gets an error message ("Page not found" or nothing happens). The phone doesn't know what myapp:// means because the app isn't there to tell it.

    • Insecurity: Any app can claim myapp://. If a user installs a malicious app that claims the same scheme, it could hijack your traffic.

Universal link

• These are the modern standard. Apple calls them Universal Links; Android calls them App Links. They solve the problems of traditional URI schemes.

• Format: https://www.myapp.com/path/to/content

• How it works: These are standard web links (HTTP/HTTPS). The mobile operating system verifies that your app "owns" that website domain via a file uploaded to your web server.

• The "Magic" Behavior:

  • If the app is installed: The OS detects the URL, sees the verified app is installed, and immediately opens the app to that content (bypassing the browser).

  • If the app is NOT installed: The link acts like a normal web link. It opens Safari or Chrome and takes the user to your mobile website.

• The Benefits:

  • Graceful Fallback: No error messages. Users always get content, either in the app or on the web.

  • Security: Only the owner of the website domain can verify the app, so no other app can hijack your links.