# Deep link

> A deep link is a URL that opens a specific screen inside an app rather than a website. In QR codes they appear as custom schemes like upi://pay or as universal links: normal https URLs that the OS routes into an installed app and that fall back to the web when it is absent.

Source: https://useqr.app/glossary/deep-link · Last reviewed 2026-08-21 · UseQR is free forever, no signup.

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## Two kinds, one crucial difference

**Custom schemes** (`myapp://…`, `upi://pay?…`, `tg://resolve?…`) go straight to the app,
and go nowhere when the app is missing. The scan either errors or silently does nothing,
and there is no page to explain what should have happened.

**Universal links (iOS) / App Links (Android)** are ordinary `https://` URLs that the app's
developer has verified for their domain. Installed app → the link opens in-app; not
installed → the same URL loads in the browser. This built-in fallback is why
`https://wa.me/447700900123` beats `whatsapp://send?phone=…` on a printed
[WhatsApp code](/whatsapp-qr-code), and why UseQR's typed generators emit the https form
wherever one exists.

The main exception is payments: [UPI codes](/upi-qr-code) use the bare `upi://pay` scheme by
design, because the ecosystem guarantees a handler and app choice is the point.

## Deep links in practice

- Prefer the `https://` form whenever the platform offers one; the paper fallback matters
  more than the app-open elegance.
- For "download our app", encode a store link or a smart routing page: see
  [app download codes](/app-download-qr-code) and
  [device-dependent codes](/docs/how-to/how-to-make-one-qr-code-do-different-things-by-device).
- Some in-app scanners refuse unknown custom schemes outright; always
  [test the payload](/validate) on both platforms before printing.

## FAQ

### Can a QR code open an app directly?
Yes, encode a deep link. A universal/App Link (https URL) opens the installed app and falls back to the browser otherwise; a custom scheme like myapp:// opens the app but fails with nothing to show when it is not installed.

### Why does my app QR code do nothing on some phones?
Almost always a custom-scheme payload on a phone without the app, or an in-app scanner that blocks unknown schemes. Switch to the https universal-link form so every phone at least reaches a web page.

## Try it

- https://useqr.app/url
- https://useqr.app/whatsapp
- https://useqr.app/upi
- https://useqr.app/validate