Select Page

Unique Organization Identifier (UOI)

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

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. For a visual representation of real estate industry MLSs and their UOI information, you can view the RESO Certification map:


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) from version 1.5 and beyond.

Unique Organization Identifier API

You can access the API for the RESO UOI (formerly OUID) to receive basic information about organizations along with their UOIs. The UOI API can be used to extract active and inactive information about organizations.

Parameters available for data query are as follows: ouid, active, org, type, city, state, country and zip. This is a public API. No credentials are required to query UOI data. Last updated: 3/11/2023.

Parameter Description


ouid Search by Unique Organization ID (currently OUID; soon to be UOI).
assoc2mls Search by association to an MLS organization.
Example 1:
Example 2:
active Search for active or inactive organizations.
Example of Active:
Example of Inactive:
org Search by an organization’s name or a portion of the name.
Example 1:
Example 2: County
type Search by organization type.
Example 1: Association
Example 2: or Provincial Association
Example 3:


Other types include Brokerage, Commercial, Pooled Platform and Technology Company.

city Search by an organization’s city.
state Search by the organization’s state.
country Search by the organization’s country.
Example 1:
Example 2:
zip Search by an organization’s ZIP or postal code.
start-date Returns all records updated on and after the date requested. Date format: YYYY-MM-DD.
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:
Example 2:
output To access the UOI data in JSON format. XML is the default output.
All parameters can be combined to allow for specific queries:

All listings are available by plainly requesting:

Note: If accessing the UOI database from a third-party product, the application expects the User Agent header with a valid value.


The XML Markup

  <name>Anchorage Board Of REALTORS</name>
   <address>3340 Arctic Blvd, #101</address>

The JSON Markup

	"name":"Anchorage Board Of REALTORS",
		 "address":"3340 Arctic Blvd, #101",
"copyright":"2020 RESO. All rights reserved"}

UOI API Update Request Form


    Rick Sherwood
    Allen Wright
    Bill Kellogg
    Clint Skutchan