Download the ontology

Ontology files

Ontology formats

  • OBO files are human-readable (in addition to machine-readable) and can be opened in any text editor.
  • OWL files can be opened with Protégé.
Name Permanent URL Description
go-basic.obo Filtered, for use with legacy tools
go.obo Core ontology (OBO Format)
go.owl Core ontology (OWL RDF/XML)
go-plus.owl Core plus additional axioms, vetted


This is the basic version of the GO, filtered such that the graph is guaranteed to be acyclic and annotations can be propagated up the graph. The relations included are is a, part of, regulates, negatively regulates and positively regulates. This version excludes relationships that cross the 3 GO hierarchies. This version should be used with most GO-based annotation tools.

go.obo and go.owl

These files contain the core GO ontology in two formats, OBO and OWL-RDF/XML. This view includes relationships not in the filtered version of GO including has_part and occurs_in. Many of these relationships may not be safe for propagating annotations across, so this version should not be used with legacy GO tools. This version excludes relationships to external ontologies.


This is the fully axiomatised version of the GO. It includes cross-ontology relationships (axioms) and imports additional required ontologies including ChEBI, Cell Ontology and Uberon. It also includes a complete set of relationship types including some not in go.obo/go.owl. This version is only available in OWL format.


GO slims are subsets of terms in the ontology. GO subsets give a broad overview of the ontology content without the detail of the specific fine grained terms. More information in the GO subset guide.

Cross-references of GO to other classification systems

Many GO classes have been cross-referenced (mapped) to a number of external classification systems. The cross-references of external classification systems to GO page contains more information and links to the cross-reference2GO files.

Snapshot Editions

As of April 2019, the standard PURLs for GO will resolve to the monthly (release) version. If you have need to access the snapshot (daily) version, use /snapshot/ in the URL. For example:

  • OBO format tools in GitHub: a wrapper for the Java (OWL-API) implementation of a parser for OBOF1.4 syntax and an implementation of the OBOF1.4 mapping to OWL (uses the OWL API)
  • OWL API in Github: a Java API for creating, manipulating and serialising OWL Ontologies.