# RESO (Real Estate Standards Organization)

**Canonical:** https://apis.io/providers/reso/  
**Website:** https://www.reso.org/  
**APIs profiled:** 2

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.

## Kin Score — 47.2 / 100 (developing)

Scored 2026-08-20 under rubric 0.12.0. Trend: flat (+0.0 from 47.2).

| Facet | Score |
|---|---|
| Discoverability | 66.7 |
| Contract Quality | 45.1 |
| Governance | 18.2 |
| Contract Governance | 18.2 |
| Operational Transparency | 31.6 |
| Developer Ergonomics | 80.4 |
| Commercial Clarity | 34.2 |
| Access Clarity | 34.2 |

## Agent readiness — 43.8 (agent-ready)

| Dimension | Value |
|---|---|
| Spec Presence | yes |
| Agentic Access | no |
| Reversibility Documented | no |
| MCP Server | verified |
| Auth Clarity | yes |
| Idempotency | no |
| Error Semantics | documented |
| OpenAPI Examples | no |
| Rate Limit Signal | no |
| Event Surface Described | yes |
| Agent Skills | derived |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |

## APIs (2)

- **RESO Web API** — 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...
- **RESO Cloud MCP Server** — 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...

## MCP servers (1)

- **RESO MCP server manifest (hosted cloud server + local stdio server)**

## Security (2)

- **Reso Authentication** — oauth2/http · 3 schemes
- **Reso Domain Security** — TLSv1.3 · DMARC

## Tags

Real-Estate, United States, RESO, MLS, Property Listings, Data Standards, OData, Industry Body, IDX, PropTech

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/reso/). Scores are computed from the provider's own public artifacts under a published rubric.