AllegroGraph is a closed source triplestore which is designed to store RDF triples, a standard format for Linked Data.

[6] It is also the storage component for the TwitLogic project[7] that is bringing the Semantic Web to Twitter data.

[8] AllegroGraph was developed to meet W3C standards for the Resource Description Framework, so it is properly considered an RDF Database.

[12] AllegroGraph has client interfaces for Java, Python, Ruby, Perl, C#, Clojure, and Common Lisp.

The product is available for Windows, Linux, and Mac OS X platforms, supporting 32 or 64 bits.