question

>Redirect to the web app Not sure I'm following you here. (No pun intended.) Alexa can't redirect anything anywhere. The card displayed is plain text. You can print a URL on it, but they are going to have to cut & paste it, or tediously copy it by hand. Not good usability if you are going to embed something complicated like the user ID. Your skill can certainly call to a web app. But... >Click link that stores userId in a state You seem to be talking about a user and a browser again. Not a programmatic link. My general recommendation to link an Alexa skill to web site is to do something like Firefox sync. Make up a 4 digit code unique to that user ID, store it in your back end database, and verbally repeat it to the user along with a simple URL to your web site. On the web site, ask them to login and enter the 4 digit code. Consult your back end database and make the connection. I describe that in a little more detail in my book ( http://www.amazon.com/How-Program-Amazon-Echo-Development-ebook/dp/B011J6AP26 ) but that's the gist of it.

You can now do this or something very similar with account linking: https://developer.amazon.com/public/solutions/alexa/alexa-skills-kit/docs/linking-an-alexa-user-with-a-user-in-your-system