From GO Public
Can I download the GO?
To download the GO please follow the 'downloads' link on the GO web site.
The GO vocabularies, association tools and documentation are freely available and have been placed in the public domain. The GO is copyrighted to protect the integrity of the vocabularies, which means that changes to the GO vocabularies need to be done by GO developers. However, anyone can download the GO and use the ontologies in their annotation or database system. The GO is available in several formats including parsable flatfiles, as tables for a MySQL database and as XML.
I'd like to integrate the GO files into a commercial application. Do I need a licensing agreement?=
The Gene Ontology vocabularies and gene product annotations are available to all public and private sector users, with no licensing requirements. We do ask that you cite the GO Consortium: see 'Cite or redistributeGO' at the GO web site. Also, please do not make any changes to the vocabularies; instead, please contact us to suggest changes by e-mail to the GO helpdesk.