Description

From front page:

BibSonomy is a system for sharing bookmarks and lists of literature. When discovering a bookmark or a publication on the web, you can store it on our server. You can add tags to your entry to retrieve it more easily. This is very similar to the bookmarks/favorites that you store within your browser. The advantage of BibSonomy is that you can access your data from whereever you are. Furthermore, you can discover more bookmarks and publications from your friends and other people.

Web api detailed at: http://www.bibsonomy.org/help/doc/api.html

Openness

Not open. Website says:

We offer a benchmark dataset in form of an SQL dump to interested people. Before you get access to our dataset, you have to sign up our license agreement and send it via fax to our office.

The license agreement does not permit commercial reuse.