KEGG API (application programming interface) allows customization of KEGG-based analysis, such as for searching and computing biochemical pathways in cellular processes or analyzing the universe of genes in the completely sequenced genomes.

Restriction: KEGG API is provided for academic use by academic users belonging to academic institutions.


The REST-style KEGG API may be supplemented with KEGG WebLinks for obtaining HTML pages. Please refer to the following documents.

Update history
June 1, 2017PubMed is included in link, Linked db displayed in info
December 1, 2016New output format of list for GENES
October 1, 2016RPAIR removed
February 1, 2016New version of link and conv without using LinkDB
September 1, 2015NCBI-ProteinID added to conv
July 1, 2014DGROUP added
June 1, 2014RDF format supported for link in KEGG MEDICUS
April 1, 2014NDC (National Drug Code) added to DDI search
April 1, 2013KEGG MEDICUS API released
February 1, 2013(WebLinks) Pathway map coloring by POST method
January 18, 2013KGML file retrieval, genes database in conv and link
July 25, 2012HTTP status code implemented
July 17, 2012Added: /find/<database>/<query>/<option>
July 6, 2012Added: /list/<database>/<org>
June 20, 2012  First release

Past announcements

Notice to KEGG API users: conv and link problems

Since around August 21, the update of the LinkDB database at GenomeNet has become unstable due to the huge increase of the data size. As the result, the conv and link operations of KEGG API sometimes do not return any result.

We are working on a new method that does not depend on LinkDB.
In the meantime please report any problems through the KEGG/GenomeNet feedback form.

Posted on September 22, 2015

A new version of link and conv operations is released.

This version does not include indirect links that were computationally generated in LinkDB, such as:
which no longer works. Instead, please use the combination of:

Posted on February 1, 2016
Updated on February 24, 2016

Transition from SOAP to REST

In the KEGG release 63.0 on July 1, 2012 a new version of the KEGG API was made available. It is a REST-based API service, replacing the previous SOAP-based API service.

The new service contains most of the capabilities of the previous service, and provides additional features for systematically handling KEGG identifiers. For example,
will list the entire set of human genes,
will convert the entire set of KEGG human gene identifiers to NCBI gi numbers (and vice versa), and
will identify KEGG pathway maps that contain each of the human genes. It is also possible to limit the gene set by changing "hsa" to "hsa:10" for a single gene, "hsa:10+hsa:100" for two genes, etc.

The previous SOAP-based API service has not been updated for five years (see ChangeLog) and has become obsolete in certain aspects. Because the original developer is no longer with us at KEGG, we have decided to move to the new service with a much simpler design. The old service will continue to be accessible for six months, until December 31, 2012.

Posted on June 4, 2012
Revised on July 1, 2012

Last updated: June 1, 2017