A deep link is a link that drops someone directly onto a specific piece of content rather than a starting point. On the web, any link to an inner page, like a single product, is technically a deep link. Today the term mostly refers to links that open a particular screen inside a mobile app, such as a specific order in a delivery app, instead of just launching the app.
How app deep links work
There are two main approaches:
- Custom URL schemes, such as
myshop://product/123. The app registers the scheme with the phone. They are simple, but if the app is not installed the link fails, and any app can claim the same scheme. - Verified web links: Apple's Universal Links and Android App Links. The link is an ordinary HTTPS URL on your own domain. You publish a small file on your site (
apple-app-site-associationfor iOS,assetlinks.jsonfor Android) proving the app and domain belong together. If the app is installed, the phone opens the matching screen; if not, the same URL simply loads your web page.
"Deferred deep linking" goes one step further: someone without the app taps the link, installs the app, and lands on the intended screen on first launch. That needs a third-party linking service or custom work, because the phone does not carry the destination through the app store by itself. Firebase Dynamic Links, a popular free option, was shut down by Google in 2025.
An example: a salon with a booking app
A salon chain sends a reminder text: "Your colour appointment is tomorrow. Reschedule here." The link is https://book.salonname.com/appointments/8841. Customers with the app see that appointment open in the app; customers without it get the same appointment on the mobile website. Nobody lands on a generic homepage and has to hunt.
When deep links matter for a small business
If you only have a website, you already deep link every time you share a page URL rather than the homepage, and that habit is worth keeping in emails, ads and QR codes. App deep linking only matters once you ship a native app, and then it is close to essential for notifications, emails and ads.
Deep-linking mistakes
- Linking campaigns to the homepage when a specific page matches the message.
- Using only a custom scheme, so people without the app get an error.
- A broken association file (wrong path, redirect, or wrong content type), which silently makes links open in the browser.
- App screens with no web equivalent, leaving non-app users at a dead end.
Related terms
- Native app: where app deep links lead.
- URL: verified deep links are normal web addresses.
- QR code: a common way to deliver a deep link offline.
- Progressive web app: an app-like site that uses plain URLs.