Worldcat is an very large bibliographic service combining the catalogue of a large number of different institutions around the world. From their site (2007-08-22):
At the center of FirstSearch is WorldCat, a cooperative database of bibliographic records contributed by more than 57,000 libraries, making it the world’s largest, most complete, and most consulted library union catalog. Your users can quickly find what they’re looking for among the 88 million global information sources in all formats—books, full text, electronic books and journals, Web-based articles, and audio and video recordings—from the full range of recorded history.
Openness: Not Open
Free search of the catalogue is allowed via the worldcat website
However institutions must buy access to worldcat via the FirstSearch service .
The underlying data is certainly not open (even if one were able to extract a significant portion of it).
Worldcat terms are at: .
Relevant section is:
A. Data. OCLC grants you a nonexclusive, nontransferable license to use Data solely for Non-Commercial Use. The following activities are prohibited and you agree not to engage in (or permit) such activities:
(i) use of Data for Commercial Use, in any manner not expressly authorized by these Terms or in any unlawful manner;
(ii) use of Data for cataloging;
(iii) making more than one (1) copy per screen display;
(iv) use of bots, spiders, or other automated information-gathering devices or programming routines to "mine" or harvest material amounts of Data;
(v) distribution, display or disclosure of Data except to the extent reasonably incidental to Non-Commercial Use; and
(vi) permanent or long-term storage of Data (including, but not limited to, creation of or repackaging in a database containing material amounts of Data).
See for discussion and background information on this decision.