RESO (Real Estate Standards Organization)

aid: reso
url: https://raw.githubusercontent.com/api-evangelist/reso/refs/heads/main/apis.yml
name: RESO (Real Estate Standards Organization)
kind: company
description: 'RESO, the Real Estate Standards Organization, is the United States industry body that writes and certifies the
  machine-readable contract for residential real estate data. It publishes the RESO Data Dictionary (the field, enumeration
  and lookup vocabulary) and the RESO Web API (an OData 4.0/4.01 profile, Web API Core 2.0.0 ratified Jan 2021 and 2.1.0 ratified
  Dec 2023), plus the RESO Common Format, EntityEvent replication, Push Replication with Webhooks, Validation Expressions
  and the URN-based Universal Parcel Identifier (UPI). NAR Policy Statement 7.90 requires MLSs owned and operated by associations
  of REALTORS to implement the Data Dictionary and the Web API and to adopt new releases within one year of ratification,
  which makes this the only mandated machine-readable API contract in the API Evangelist sector study that is imposed by an
  industry body rather than a regulator. RESO itself operates no production API and holds no listing data: it certifies other
  people''s servers. Its specifications, reference OData EDMX metadata and Data Dictionary JSON are freely and anonymously
  downloadable from transport.reso.org and the RESOStandards GitHub organization (a EULA click-through wraps the reso.org
  copies), and the certification directory at reso.org/certificates and certification.reso.org is public without login. Reachability
  is the separate fact: a RESO-certified endpoint is run by a local MLS, and credentials for it are issued only after a data
  licence with that MLS is signed, so certification here means conformance, never public access.'
image: https://www.reso.org/wp-content/uploads/2021/04/RESO-Logo-Fullname_Horizontal_Blue.png
tags:
- Real Estate
- United States
- RESO
- MLS
- Property Listings
- Data Standards
- OData
- Industry Body
- IDX
- PropTech
created: '2026-07-26'
modified: '2026-07-26'
specificationVersion: '0.19'
apis:
- aid: reso:reso-web-api
  name: RESO Web API
  description: 'The RESO Web API is the ratified transport standard for real estate data, defined as a profile of OData 4.0/4.01
    (Web API Core 2.0.0 and 2.1.0). Servers MUST expose an OData XML metadata document at /$metadata relative to their service
    root, MUST return JSON for data requests, MUST use TLS 1.2 or above, and MUST authenticate with OAuth2 Bearer tokens or
    the Client Credentials grant (RCP-026). RESO publishes the specification, the reference Data Dictionary EDMX metadata
    and the RESO Commander testing tool, but RESO operates NO endpoint of its own and no base URL is documented here for that
    reason - every conformant server is run by an individual MLS or data provider. Access is not self-serve: RESO states that
    "access to data from the Web API is gained through local MLSs" and that "RESO does not provide MLS real estate data. RESO
    creates data standards." The api.reso.org host that appears in the specification text is an illustrative example only
    and does not resolve.'
  humanURL: https://www.reso.org/reso-web-api/
  tags:
  - Web API
  - OData
  - MLS
  - Transport
  - Certification
  properties:
  - type: Specification
    url: https://github.com/RESOStandards/transport/blob/main/proposals/web-api-core.md
    name: RESO Web API Core specification (RCP-37)
  - type: Documentation
    url: https://www.reso.org/reso-web-api/
  - type: Documentation
    url: https://transport.reso.org/
  - type: Metadata
    url: openapi/reso-dd-2.1-enum.xml
    name: RESO Data Dictionary 2.1 reference OData EDMX metadata (enumerations)
  - type: Metadata
    url: openapi/reso-dd-2.1-lookup-resource.xml
    name: RESO Data Dictionary 2.1 reference OData EDMX metadata (Lookup Resource)
  - type: Metadata
    url: openapi/reso-dd-2.0-enum.xml
    name: RESO Data Dictionary 2.0 reference OData EDMX metadata (enumerations)
  - type: Metadata
    url: openapi/reso-dd-2.0-lookup-resource.xml
    name: RESO Data Dictionary 2.0 reference OData EDMX metadata (Lookup Resource)
  - type: Metadata
    url: openapi/reso-dd-1.7-enum.xml
    name: RESO Data Dictionary 1.7 reference OData EDMX metadata (enumerations)
  - type: Metadata
    url: openapi/reso-dd-1.7-lookup-resource.xml
    name: RESO Data Dictionary 1.7 reference OData EDMX metadata (Lookup Resource)
  - type: DataModel
    url: openapi/reso-dd-2.1.json
    name: RESO Data Dictionary 2.1 machine-readable reference (JSON)
  - type: DataModel
    url: openapi/reso-dd-2.0.json
    name: RESO Data Dictionary 2.0 machine-readable reference (JSON)
  - type: DataModel
    url: openapi/reso-dd-1.7.json
    name: RESO Data Dictionary 1.7 machine-readable reference (JSON)
  - type: Webhooks
    url: https://github.com/RESOStandards/transport/blob/main/proposals/webhooks-push.md
    name: Push Replication with EntityEvent and Webhooks (RCP-28)
  - type: Specification
    url: https://github.com/RESOStandards/transport/blob/main/proposals/entity-events.md
    name: EntityEvent Resource and Replication (RCP-27)
  - type: Specification
    url: https://github.com/RESOStandards/transport/blob/main/proposals/data-dictionary.md
    name: RESO Data Dictionary specification (RCP-36)
  - type: Tooling
    url: https://github.com/RESOStandards/web-api-commander
    name: RESO Commander - Web API certification and testing tool
  - type: ReferenceImplementation
    url: https://github.com/RESOStandards/reso-web-api-reference-server
    name: RESO Web API and Data Dictionary compliant reference server (self-hosted, localhost only)
  - type: Certification
    url: https://www.reso.org/certificates/
    name: Public directory of RESO-certified organizations
  - type: Conventions
    url: conventions/reso-conventions.yml
    name: RESO Web API cross-cutting conventions (OData query options, pagination, versioning, errors)
  - type: ErrorCatalog
    url: errors/reso-problem-types.yml
    name: OData JSON error envelope and Web API Core response-code table
  - type: Authentication
    url: authentication/reso-authentication.yml
    name: RESO Web API authentication profile (OAuth2 Bearer / Client Credentials, RCP-026)
  - type: DataModel
    url: data-model/reso-data-model.yml
    name: Derived Data Dictionary 2.1 entity-relationship graph (44 entities, 146 relationships)
  - type: Webhooks
    url: asyncapi/reso-webhooks.yml
    name: EntityEvent (RCP-27) and Push Replication with Webhooks (RCP-28) event surface
- aid: reso:reso-cloud-mcp
  name: RESO Cloud MCP Server
  description: 'The RESO Cloud MCP Server is the one production API endpoint RESO itself operates. It speaks the Model Context
    Protocol over Streamable HTTP at https://services.reso.org/mcp and exposes the RESO toolchain to AI agents - authenticate,
    query, metadata, create, update, delete and parse-filter - so an agent can work against any RESO-certified OData server
    without knowing OData syntax. It is a broker, not a data source: every tool call takes a target server URL and that server''s
    credentials, and RESO stores no listing data behind it. Access is beta and gated on an API key issued by RESO on request
    to dev@reso.org, available to RESO members and conference attendees; an anonymous tools/list returns HTTP 401 with a JSON-RPC
    error pointing at that address. The same tool interfaces are available offline via the local stdio server (@reso-standards/reso-mcp-server),
    which adds the validate, run-compliance and metadata-report certification tools.'
  humanURL: https://tools.reso.org/packages/reso-mcp-server
  baseURL: https://services.reso.org/mcp
  tags:
  - MCP
  - AI Agents
  - OData
  - Certification
  - Tooling
  properties:
  - type: MCPServer
    url: mcp/reso-mcp.yml
    name: RESO MCP server manifest (hosted cloud server + local stdio server)
  - type: ToolCrosswalk
    url: mcp/reso-tool-crosswalk.yml
    name: MCP tool to OData request-form crosswalk
  - type: Documentation
    url: https://github.com/RESOStandards/reso-tools/blob/main/reso-mcp-server/doc/GUIDE.md
    name: RESO MCP Server User Guide
  - type: Documentation
    url: https://github.com/RESOStandards/reso-tools/blob/main/reso-mcp-server/README.md
    name: RESO MCP Server README
  - type: Authentication
    url: authentication/reso-authentication.yml
    name: API-key bearer auth on the cloud server; OAuth2 pass-through to target servers
  - type: SourceCode
    url: https://github.com/RESOStandards/reso-tools/tree/main/reso-mcp-server
common:
- type: DomainSecurity
  url: security/reso-domain-security.yml
- type: Website
  url: https://www.reso.org/
- type: About
  url: https://www.reso.org/about-reso/
- type: Documentation
  url: https://transport.reso.org/
- type: Specification
  url: https://www.reso.org/specs/
  name: RESO specifications directory
- type: Specification
  url: https://github.com/RESOStandards/transport/blob/main/proposals/reso-common-format.md
  name: RESO Common Format (RCP-25)
- type: Specification
  url: https://github.com/RESOStandards/transport/blob/main/proposals/validation-expressions.md
  name: Web API Validation Expressions (RCP-19)
- type: DataDictionary
  url: https://www.reso.org/data-dictionary/
- type: DataDictionary
  url: https://dd.reso.org/
  name: RESO Data Dictionary Wiki
- type: Identifiers
  url: https://www.reso.org/universal-parcel-identifier/
  name: Universal Parcel Identifier (UPI) 2.0, URN-based
- type: Tooling
  url: https://upi.reso.org/builder/
  name: RESO UPI Builder
- type: Certification
  url: https://www.reso.org/certification/
- type: Certification
  url: https://certification.reso.org/
  name: RESO Analytics certification portal and endorsement directory
- type: Pricing
  url: https://www.reso.org/certification-fee-schedule/
  name: RESO certification fee schedule (complimentary for members)
- type: Membership
  url: https://www.reso.org/membership/
- type: TermsOfService
  url: https://www.reso.org/eula/
  name: RESO End-user License Agreement gating spec downloads from reso.org
- type: GitHubOrganization
  url: https://github.com/RESOStandards
- type: Blog
  url: https://www.reso.org/blog/
- type: BlogRSS
  url: https://www.reso.org/feed/
- type: Regulation
  url: https://www.nar.realtor/handbook-on-multiple-listing-policy/operational-issues-section-12-real-estate-transaction-standards-rets-policy-statement-790
  name: NAR Policy Statement 7.90 - RESO Standards implementation requirement for association-owned MLSs
- type: Email
  url: mailto:dev@reso.org
  name: RESO developer and certification contact
- type: DeveloperPortal
  url: https://tools.reso.org/
  name: RESO Tools - developer portal for the open-source RESO toolchain
- type: APIReference
  url: https://dd.reso.org/
  name: RESO Data Dictionary Wiki - per-resource, per-field reference
- type: GettingStarted
  url: https://www.reso.org/developer-resources/
  name: RESO developer resources
- type: Support
  url: https://www.reso.org/support/
- type: HelpCenter
  url: https://www.reso.org/developer-faqs/
  name: RESO developer FAQs
- type: SignUp
  url: https://www.reso.org/join/
  name: Join RESO (membership is the gate on certification, not on reading the standards)
- type: Roadmap
  url: https://transport.reso.org/
  name: RESO Transport specifications - 7 ratified standards and 14 in-progress change proposals
- type: ChangeLog
  url: https://tools.reso.org/releases/
  name: RESO Tools release notes
- type: ChangeLog
  url: changelog/reso-changelog.yml
  name: Structured changelog - tooling releases, specification ratifications and policy milestones
- type: Lifecycle
  url: lifecycle/reso-lifecycle.yml
  name: Versioning policy, ratification process, deprecation notices and endorsement expiry
- type: Deprecation
  url: https://transport.reso.org/versioning/
  name: RESO versioning and breaking-change policy (the deprecation model for the standards)
- type: Conventions
  url: conventions/reso-conventions.yml
  name: RESO Web API cross-cutting conventions
- type: ErrorCatalog
  url: errors/reso-problem-types.yml
  name: OData JSON error envelope and Web API Core response-code table
- type: Authentication
  url: authentication/reso-authentication.yml
  name: RESO authentication profile
- type: Conformance
  url: conformance/reso-conformance.yml
  name: Cross-cutting standards the RESO Web API profile conforms to
- type: Packages
  url: packages/reso-packages.yml
  name: First-party RESO client libraries and tools across npm, Packagist and GitHub Releases
- type: SDKs
  url: packages/reso-packages.yml
  name: Official RESO SDKs - TypeScript (@reso-standards/*), PHP (reso/reso-php), Java (RESO Commander)
- type: CLI
  url: cli/reso-cli.yml
  name: reso-cert certification CLI, reso-mcp and the legacy RESO Commander
- type: Sandbox
  url: sandbox/reso-sandbox.yml
  name: Self-hosted RESO reference server, seeded synthetic data and compliance profiles
- type: Components
  url: components/reso-components.yml
  name: Prebuilt client-side surfaces - web client, desktop client, proxy and the UPI Builder
- type: DataModel
  url: data-model/reso-data-model.yml
  name: Derived Data Dictionary 2.1 entity-relationship graph
- type: Webhooks
  url: asyncapi/reso-webhooks.yml
  name: EntityEvent and Push Replication webhook event surface
- type: AgentSkill
  url: skills/_index.yml
  name: RESO agent skills index
- type: AgentSkill
  url: skills/reso-query-a-certified-server.md
  name: Query a RESO-certified Web API server
- type: AgentSkill
  url: skills/reso-replicate-with-entityevent.md
  name: Replicate a RESO feed with EntityEvent and webhooks
- type: AgentSkill
  url: skills/reso-certify-a-server.md
  name: Certify a server against RESO standards
- type: LLMsTxt
  url: llms/reso-llms.txt
  name: Generated llms.txt for RESO (RESO publishes none)
- type: SecurityAudit
  url: security/reso-security-audit.yml
  name: RESO Tools published security audit log (findings, severities and accepted risks)
- type: SecurityAudit
  url: https://tools.reso.org/security/
  name: RESO Security Audit Log
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com