OpenCalais : Calais is a rapidly growing toolkit of capabilities that allow you to readily incorporate state-of-the-art semantic functionality within your blog, co...
pump.io : Social server with an ActivityStreams API. It's a stream server that does most of what people really want from a social network.
kimono : Turn websites into structured APIs from your browser in seconds
Anything to Triples : Anything To Triples (any23) is a library, a web service and a command line tool that extracts structured data in RDF format from a variety of Web docu...
Hoppscotch : A free, online, open source API request builder