QR code glossary · Formats and payloads
Deep link
Also called: Mobile deep link
Definition
A deep link is a link that opens a specific screen or item inside a mobile app, such as a product page, rather than the app’s home screen or a website; in a QR code it is usually an ordinary https address that the phone hands to the installed app.
How it works
There are three common kinds:
- Custom URI schemes, such as
myapp://product/42. They work only when the app is installed; otherwise the link fails, and not every camera app will open them. - Universal Links on iOS: normal https addresses on a domain the app has claimed. The site publishes an
apple-app-site-associationfile under/.well-known/; if the app is installed, the link opens it, and if not, the same address opens the website. - Android App Links: https addresses verified through a Digital Asset Links file,
assetlinks.json, also under/.well-known/. Once verified, they open the app directly without asking which app to use. Android supports them from Android 6 on devices with Google services.
“Deferred” deep linking goes a step further: it sends someone without the app to the store and, after install, opens the right screen. That is not built into either platform; it needs a third-party attribution service or SDK.
Why it matters
For printed codes, use https Universal Links and App Links rather than custom schemes. The same code then works for everyone: people with the app land in it, and people without it get the web page, which can offer the download.
Redirects add a wrinkle. When a dynamic code’s short link redirects to a Universal Link or App Link, whether the phone opens the app or the website depends on the platform, the browser and how the link was opened. Test on real iPhones and Android phones, with the app installed and without it, before printing.
In CirculateQR
Device routing can send iPhones and Android phones to different destinations from one code, such as each platform’s app store or its own deep link.
Related terms
- Smart routingSmart routing is a feature of dynamic QR codes that sends each scan of the same printed code to a different destination according to rules, such as the phone’s operating system, its language setting, the time of day or the scanner’s approximate location; routing by location is often called geo-routing.
- RedirectA redirect is an HTTP response with a 3xx status code and a Location header that tells the browser to load a different address; it is how a dynamic QR code’s short link forwards each scan to the code’s current destination.
- Dynamic QR codeA dynamic QR code is a QR code that encodes a short link to a redirect service instead of the final content, so the destination can be changed after printing and each scan can be counted, for as long as the service keeps the link active.
- Short URLA short URL is a brief web address, such as example.com/r/A7K2Q9, that a server forwards to a longer destination; dynamic QR codes encode one so the printed pattern stays small and the destination can change without reprinting.
Learn more
- App Store QR code generator: One code for the App Store and Google Play.
- Smart routing in CirculateQR: Send each device to the right link.
- Routing QR code scans by device: Rules, defaults and testing.
Sources
Last updated . Written by the CirculateQR team; technical facts follow the sources listed above. Example codes and sizes are computed with the open-source qrcode encoder that CirculateQR uses. Spotted something wrong? Email support@circulateqr.com. QR Code is a registered trademark of DENSO WAVE INCORPORATED.
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