The SEER API is a RESTful Web service that supports various SEER Program data sets and mapping. This service is available to developers who wish to incorporate SEER resources into their own systems. These resources include databases and tools developed to enhance registry operations and quality improvement. The SEER API is designed for integration into registry computer systems and is not designed to be accessed by end-users.

The goal of SEER API is to provide a centralized repository of SEER Program tools that is available to all programming environments and operating systems. The API is based on REST principles, therefore, it is very easy to write and test applications. You can use your browser to access URLs and to test APIs. Any programming language that can read HTTP data from a URL can use web services. Results are returned in JSON format which can be easily parsed and interpreted. See the Usage page for language-specific examples.

The SEER API powers a variety of SEER tools, including:

• Glossary for Registrars
• Hematopoietic and Lymphoid Database
• Observational Research in Oncology Toolbox
• SEER*RSA
• SEER*Rx Interactive Antineoplastic Drugs Database

The Surveillance, Epidemiology and End Results (SEER) Program is a premier source for cancer statistics in the United States. The SEER Program collects information on incidence, prevalence and survival from specific geographic areas representing 28 percent of the US population and reports on all these data plus cancer mortality data for the entire country.

June 17, 2025

• The NAACCR endpoints were changed. The data is now based on the NAACCR Data Dictionary API. See the /rest/naaccr for details on the new endpoints.

October 30, 2024

• Updated the recode endpoint to support additional site recode algorithms. In addition to SEER site recode, the API now also supports the International Classification of Childhood Cancer and Adolescents and Young Adults (AYA) site recodes. See the /rest/recode for more information.

July 21, 2023

• Added initial support for NAACCR 24 to the NAACCR API

June 30, 2023

• Updates to MPH calculations
  • Renamed all group IDs and names and exposed the names in the output objects.
  • Implemented 2023 updates of solid tumor rules.
  • Updated hematopoietic histology range.

March 2, 2023

• Added support for NAACCR 23 to the NAACCR API