node-deeplink

Easily create express endpoint to handle mobile deeplinks in your web server

Takes away the pain of forwarding users to the right app store / mobile app depending on their platform.

Important update

In ios >= 9, Apple has made it impossible to provide a smooth user experience to redirect user to app / fallback to app store from javascript. Their clear direction is pushing towards using Universal Links instead.

For more details, see issue #9 and this blog post.

To get the best user experience, it's probably better to look at Universal Links for ios and App Links for Android.

If you already started using Universal Links, you can still use this module as a fallback mechanism for older ios versions.

Use case

Suppose you have a custom url scheme app:// handled by your mobile apps. You want to create a universal "smart" link that will know where to send the user:

• If the user has the app installed, open the app with the deeplink.
• If the user doesn't have the app installed, send to the app store to download the app (google play / itunes).
• If the user doesn't have a supported phone, send to a fallback url.

Usage

Example:

var express = require('express');
var deeplink = require('node-deeplink');

var app = express();

app.get(
  '/deeplink',
  deeplink({
    fallback: 'https://cupsapp.com',
    android_package_name: 'com.citylifeapps.cups',
    ios_store_link:
      'https://itunes.apple.com/us/app/cups-unlimited-coffee/id556462755?mt=8&uo=4'
  })
);

This example creates an endpoint GET /deeplink in your web server.

Assuming your server address is https://acme.org, you can use the link https://acme.org/deeplink?url=app://account so when users will open it the app will open with app://account deeplink or the users will be redirected to download the app in case they don't have it.

Note on url encoding: to avoid problems with url parsing libraries, the deep link (app://... part) has to be url encoded. node-deeplink will decode the url correctly. So, in the above example, the link is actually https://acme.org/deeplink?url=app%3A%2F%2Faccount. Here's an example of url encoder/decoder.

Available options

node-deeplink currently only supports Android and ios.

Options to pass on to node-deeplink are:

• fallback: mandatory. A fallback url in case the user is opening the link via an unsupported platform like desktop / windows phone etc. In such case, the fallback url will be opened in the user's browser like a normal link.
• android_package_name: optional. In case you want to support Android deep links, pass your app's package name.
• ios_store_link: optional. In case you want to support ios deep links, pass your app's itunes url. You can get it here.
• title: optional. Title for the intermediate html page. Defaults to an empty string.

Query params

When a request comes in, the following query params a re checked:

• url: mandatory. The deeplink url you want the user to be directed to e.g. app://account.
• fallback: optional. If available, will prefer this fallback address over the one from the options.

Behaviour

node-deeplink expects the request to contain a query param url=... so that the deeplink mechanism will work. If no such query is present then node-deeplink ignores the request and calls next() so the request will be handled by the next middleware.

node-deeplink works by first sending the user to an html page with a user-agent sniffing script. After figuring out the user's device, it redirects the to the predefined deeplink. In practice, after clicking the link, the browser will be opened for a very short moment and then the redirect will happen.

TODO

• Better user-agent discovery.
• Enable non-express use.