Unique Organization Identifier (UOI)

RESO’s Unique Organization Identifier (UOI) provides a singular ID for a growing list of individual organizations within the real estate industry. The list includes REALTOR® associations, MLSs, technology vendors, brokers and other affiliated businesses.

For example, from the UOI, you can derive how many MLSs there are in North America.

Data providers should include their UOI in data feeds so data recipients can accurately identify the organizational source (publisher) of each piece of data in an aggregated database.

Technology partners utilizing data should use the UOI to assist with the management of multiple data feeds and overlapping service areas. This helps with clear notation of data originators and allows for easier data deduplication.

Technology partners can also use a UOI to look up association-to-MLS relationships, which can be helpful when an association provides a lockbox or showing service, but the underlying data is from an MLS source that must be linked to the association’s system.

The RESO Data Dictionary includes standardized containers for the UOI (still documented as OUID at this time).

API

The RESO UOI API (fka RESO OUID API) provides basic information about organizations along with their UOI numbers.

Parameters available for data query include: ouid, active, org, type, city, state, country and zip. This is a public API. No credentials are required to query UOI data. Last updated: 11/23/2024.

Additional formats that are updated daily under the RESO Certification Map can be found on our Certification page. The plan is to replace the service here with what you see there in 2025.

Parameter Descriptions

ouid	Search by Unique Organization ID (still documented as OUID at this time). Example: https://www.reso.org/ouid/?ouid=A00000007
assoc2mls	Search by association to an MLS organization. Example 1: https://www.reso.org/ouid/?assoc2mls=M00000001 Example 2: https://www.reso.org/ouid/?assoc2mls=M00000002
active	Search for active or inactive organizations. Example of Active: https://www.reso.org/ouid/?active=1 Example of Inactive: https://www.reso.org/ouid/?active=0
org	Search by an organization’s name or a portion of the name. Example 1: https://www.reso.org/ouid/?org=mlslistings Example 2: https://www.reso.org/ouid/?org=Macon County
type	Search by organization type. Example 1: https://www.reso.org/ouid/?type=Local Association Example 2: https://www.reso.org/ouid/?type=State or Provincial Association Example 3: https://www.reso.org/ouid/?type=MLS Other types include Brokerage, Commercial, Pooled Platform and Technology Company.
city	Search by an organization’s city. Example: https://www.reso.org/ouid/?city=Dallas
state	Search by the organization’s state. Example: https://www.reso.org/ouid/?state=AR
country	Search by the organization’s country. Example 1: https://www.reso.org/ouid/?country=USA Example 2: https://www.reso.org/ouid/?country=Canada
zip	Search by an organization’s ZIP or postal code. Example: https://www.reso.org/ouid/?zip=92111
start-date	Returns all records updated on and after the date requested. Date format: YYYY-MM-DD. Example: https://www.reso.org/ouid/?start-date=2020-04-01
end-date	Returns all records updated on and before the date requested until the “start-date” or all records prior if the start date is not set. Date format: YYYY-MM-DD. Example 1: https://www.reso.org/ouid/?start-date=2020-04-01&end-date=2020-05-31 Example 2: https://www.reso.org/ouid/?end-date=2020-04-01
output	To access the UOI data in JSON format. Example: https://www.reso.org/ouid/?output=json
All parameters can be combined to allow for specific queries: https://www.reso.org/ouid/?state=NC&type=MLS https://www.reso.org/ouid/?state=CA&active=1
All listings are available in XML format by plainly requesting: https://www.reso.org/ouid/ Note: If accessing the UOI database from a third-party product, the application expects the User Agent header with a valid value.

XML Markup

<organizations>
 <organization>
  <name>Anchorage Board Of REALTORS</name>
  <ouid>A00000002</ouid>
  <assoc2mls>M00000001</assoc2mls>
  <type>LocalAssociation</type>
  <active>1</active>
  <url>www.ancboard.com</url>
  <location>
   <address>3340 Arctic Blvd, #101</address>
   <city>Anchorage</city>
   <state>AK</state>
   <zip>99503</zip>
   <country>USA</country>
  </location>
  <updated>2020-01-06</updated>
 </organization>
</organizations>

JSON Markup

{"organization":
	{
	"name":"Anchorage Board Of REALTORS",
	"ouid":"A00000002",
	"assoc2mls":"M00000001",
	"type":"LocalAssociation",
	"active":"1",
	"url":"www.ancboard.com",
	"location":
		{
		 "address":"3340 Arctic Blvd, #101",
		 "city":"Anchorage",
		 "state":"AK",
		 "zip":"99503",
		 "country":"USA"
		 },
	"updated":"2020-01-06"
	},
"copyright":"2020 RESO. All rights reserved"}

UOI API Update Request Form

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Acknowledgements

The RESO UOI is the product of a synergetic effort from industry professionals who offered their time, vision and expertise towards the formation of this project. We are thankful for the contributions of Matt Cohen, Ross Colley, Bill Kellogg, Greg Sax, Rick Sherwood, Clint Skutchan and Allen Wright.