This example shows, how to start intent from browser:

<a href="intent://host.com/path#Intent;package=com.sample.test;scheme=yourscheme;end">Start intent</a>

This intent will start app with package com.sample.test or will open google play with this package.

Also this intent can be started with javascript:

var intent = "intent://host.com/path#Intent;package=com.sample.test;scheme=yourscheme;end";
window.location.replace(intent)

In activity this host and path can be obtained from intent data:

@Override
public void onCreate(Bundle bundle) {
    super.onCreate(bundle);
    Uri data = getIntent().getData(); // returns host.com/path
}

Intent URI syntax:

HOST/URI-path // Optional host
#Intent;
    package=[string];
    action=[string];
    category=[string];
    component=[string];
    scheme=[string];
end;