ESDS Program

CEOS OpenSearch


Committee on Earth Observation Satellites (CEOS) OpenSearch is a collection of simple specifications for a simple search syntax and the sharing of Earth science data search results. The goal of the CEOS OpenSearch project is to establish common CEOS interoperability best practices for OpenSearch in order to allow for standardized and harmonized access to metadata and data of CEOS agencies, including CEOS WGISS Integrated Catalog (CWIC) and FedEO communities.

ESDS-RFC-025 CEOS OpenSearch is a Technical Note that provides information about the specification that is broadly implemented within NASA Earth science data systems, the Earth Science Information Partners (ESIP) community data systems, as well as by many other Earth science data systems from international agencies around the world.


The CEOS OpenSearch document was recommended for informational use in NASA Earth science data systems in January, 2016.

Latest Version CEOS OpenSearch Best Practice V 1.3 (November 12, 2020)
Technical Note CEOS OpenSearch
(November, 2015)
User Resources CEOS Open Search home page

CEOS OpenSearch Developer Guide V 2.0D3
OpenSearch Specification

CEOS OpenSearch Conformance Test Plan, Version 1.0
(August 28, 2018)

Earthdata OpenSearch User Interface
Enter any OpenSearch Descriptor Document (OSDD) URL as input. Then click the Search button to see a search user interface where you can add search terms, geographic and temporal constraints and other search parameters.

Earthdata OpenSearch Validation Tool


This validation tool will take an OpenSearch Descriptor Document (OSDD) URL as input. It will then download that OSDD and validate its contents against a number of specifications, extensions, best practices and development guides. Each validation has a score between 0 (failed) and 5 (perfect score). The validation functionality is also available as a web service.


NASA Earth Science Community Recommendations for Use


CEOS OpenSearch is widely implemented in the US and by many international agencies. This results in a broad base of implementation experience and provides a high degree of confidence that implementers will be able to connect to a large ecosystem. The specification is relatively simple to implement. CEOS OpenSearch is generally implemented with very simple search semantics and can work on a wide variety of data.

CEOS OpenSearch supports a seamless two step search process that allows searches to first discover data collections and then data granules (individual files).

CEOS OpenSearch uses technologies that are commonly used. HTTP requests and ATOM XML responses are sent and parsed by something as simple as a browser or as complex as fully-fledged web application.


There is a great diversity in implementations – all slightly different, leading to varied returned results, making it more difficult to compare results across implementations.

There is no data model for stored metadata or returned information. This can result in missing key information (e.g. provider contact info).


CEOS OpenSearch is applicable for use in formulating metadata searches for both collection and granule metadata.

It is meant to provide easy access to geospatial metadata catalogs.


CEOS OpenSearch is limited to simple queries based on spatial, temporal and keyword search parameters. It does not currently provide a full query language.

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