With jQuery.qrcode.js you can easily add qrcode to your webpages. It is standalone, no external services which go on and off, or add latency while loading.
Show, dont tell, here is a demo
How to Use It
First include it in your webpage with the usual script tag
Then create a DOM element which gonna contains the generated qrcode image. Lets say a div
Then you add the qrcode in this container by
jQuery('#qrcode').qrcode("this plugin is great");
This is it.