Flickcurl

"Flickcurl http://librdf.org/flickcurl/ is a C library for the Flickr API, handling creating the requests, signing, token management, calling the API, marshalling request parameters and decoding responses. It uses libcurl to call the REST web service and libxml2 to manipulate the XML responses. Flickcurl supports 100% of the 2009-04-04 version of the API (see Flickcurl API coverage) including the functions for photo/video uploading, browsing, searching, adding and editing comments, groups, notes, photosets, categories, activity, blogs, favorites, places, tags, machine tags, institutions, pandas and photo/video metadata. It also includes a program flickrdf to turn photo metadata, tags, machine tags and places into an RDF triples description."