Qddb can currently be obtained either in source (GPL version) or binary (commercial version) form. The official Qddb home page is located at http://www.hsdi.com/qddb/ and contains links to the User's Guide, download and ordering information, technical articles about Qddb's data structures and algorithms, programming information, release notes and FAQs. Several free and commercial Qddb applications are also available directly from this site.