Is it possible to use the Disqus API to get comments from a specific url?
You could always use jQuery for the AJAX calls as almost everything on Disqus is now get.
First you would have to get the thread id from using (http://disqus.com/api/docs/threads/list/):
http://disqus.com/api/3.0/threads/list.json?api_key=API_PUBLIC_KEY_HERE&forum=[shortforumid]&thread=link:[link]
The most important part is for the thread= to have link:[link] as the link: says we are using a URL.
After you get the thread id, you will have to visit (http://disqus.com/api/docs/posts/list/):
http://disqus.com/api/3.0/posts/list.json?api_key=API_PUBLIC_KEY_HERE&thread=[thread id]
Just as a reminder, you do not need to put in the brackets...
The accepted answer consists in 2 different calls to Disqus API, to avoid the limit usage you could use only 1 call for obtains a list of comments by an url: