oxo

is an Aggregator.

OxO (Ontology Xref Service) is a cross-ontology mapping service developed by EMBL-EBI's Samples, Phenotypes and Ontologies Team (SPOT). The service provides mappings between terms from different ontologies, enabling users to search for equivalent or related terms across multiple ontological resources. OxO aggregates cross-references from ontologies loaded in the Ontology Lookup Service (OLS) and enriches these with manual mappings and inference-based relationships.

Domains

biomedical, upper, biological systems

License

Warning: No license entered

Homepage

oxo

Repository

GitHub

Infores ID

infores:oxo

FAIRsharing ID

Unknown

Product Summary

Products

From this Resource
ID Name URL Category Format Description
oxo.api OxO REST API api ProgrammingInterface http RESTful API for programmatic access t...
oxo.portal OxO Web Interface oxo GraphicalInterface http Web-based interface for searching and...

Details

Ontology Xref Service (OxO)

Overview

OxO (Ontology Xref Service) is a service developed and maintained by EMBL-EBI’s Samples, Phenotypes and Ontologies Team (SPOT) for cross-ontology term mapping. The service facilitates the discovery of mappings between terms from different ontological resources, enabling data integration and interoperability across biomedical databases and tools.

Current Status

⚠️ Service Alert: As of November 2025, the OxO website is experiencing technical issues and returning HTTP 500 server errors. The service may be temporarily unavailable or under maintenance.

Purpose

OxO serves to:

  • Provide mappings between equivalent or related terms across different ontologies
  • Facilitate data integration across heterogeneous biomedical resources
  • Enable cross-ontology searches and term translation
  • Support semantic interoperability in biomedical research

Data Sources

OxO aggregates cross-reference data from:

  • Ontology Lookup Service (OLS): Cross-references embedded in ontologies
  • Manual Mappings: Curated mappings contributed by domain experts
  • Inference-Based Mappings: Automatically generated mappings based on term relationships

Key Features

Cross-Ontology Mapping

Search for equivalent or related terms across multiple ontologies, enabling translation between different vocabular systems.

Mapping Provenance

Understand the source and reliability of mappings, with information about whether mappings are:

  • Direct cross-references from ontology files
  • Manually curated by experts
  • Inferred through reasoning

Programmatic Access

REST API for integration into computational workflows and applications.

OxO is part of the SPOT suite of ontology services at EMBL-EBI:

  • OLS (Ontology Lookup Service): Repository and browser for biomedical ontologies
  • ZOOMA: Service for mapping free-text annotations to ontology terms

Information Resource ID

This resource has the Information Resource identifier: infores:oxo

Contact and Support

For questions or issues regarding OxO:

  • Email: ols-support@ebi.ac.uk
  • Organization: EMBL-EBI Samples, Phenotypes and Ontologies Team (SPOT)

Use Cases

  1. Data Integration: Mapping identifiers when merging datasets using different ontologies
  2. Ontology Alignment: Finding equivalent terms for ontology harmonization projects
  3. Cross-Database Queries: Translating queries across databases using different terminologies
  4. Semantic Interoperability: Enabling communication between systems using different vocabularies

Is this information incorrect or incomplete? Request an update.

Created: November 04, 2025 | Last modified: November 04, 2025