Apartments.com
Apartments.com is the largest United States rental-listings marketplace, owned by CoStar Group since its 2014 acquisition and operated from Arlington, Virginia as the anchor of the Apartments.com Network — a group of consumer rental sites that also includes ApartmentFinder.com, ApartmentHomeLiving.com, ForRent.com, ForRentUniversity.com, WestsideRentals.com, Apartamentos.com, After55.com and CorporateHousing.com. It sits on the demand side of the US residential value chain as an Internet Listing Service (ILS): apartment owners and property managers buy advertising, and their inventory, availability, pricing, media, concessions and fee data flows in from property management systems (Yardi, RealPage, Entrata, MRI, AppFolio, ResMan, Rent Manager, Funnel, EliseAI and others) rather than from any public API, while leads flow back out to the advertiser's CRM. Its API posture is closed. Apartments.com publishes no developer portal, no OpenAPI or OData $metadata contract, no SDK, no webhooks and no Postman collection; developer.apartments.com, developers.apartments.com and docs.apartments.com do not resolve in DNS, and api.apartments.com resolves only to the same Akamai edge that returns HTTP 403 Access Denied to every non-browser request, including robots.txt. The one documented machine-to-machine seam is the Digital Feeds Program — an approval-and-contract path in which an approved third-party feed vendor syndicates a paying advertiser's listings into Apartments.com over FTP using an XML listings feed whose specification guide is available only on request to [email protected]. A second inbound seam lets licensed agents opt in to rental-listing syndication through their own MLS (Bright MLS, ARMLS, REcolorado, OneKey MLS, SmartMLS, NorthstarMLS, MLS PIN, Garden State MLS, New Jersey MLS and Aspen Glenwood MLS are documented), which requires MLS membership. On RESO, the honest reading is absence rather than "certified but unreachable": Apartments.com does not appear anywhere in the RESO certificates list, and its own property-manager help centre returns zero results for "RESO". It is a consumer of MLS rental feeds, not a certified RESO endpoint, and no unlicensed open dataset is published.
More than an index entry, but the surface is still mostly links rather than artifacts — the cohort most likely to move a full band from modest, well-targeted work.
API Evangelist profiles Apartments.com the way a machine reads it — 2 machine-readable artifacts, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Apartments.com scores 16.9/100 (emerging), with a separate agent-readiness read of 0/100 (human only). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-07-27 · rubric v0.5
How we profile Apartments.com
Each block below is one kind of artifact we hold for Apartments.com. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
Security Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Resources
Every other property we hold for Apartments.com — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 2
Portal, sign-up, and the first successful call
Documentation 4
Reference material describing how the API behaves
Agent Surfaces 1
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 1
Pagination, idempotency, versioning, errors, and events
Build 2
SDKs, sample code, and the tooling you integrate with
Access & Security 1
Authentication, authorization, and security posture
Learn 1
Tutorials, courses, talks, and written guidance
Operate 4
Status, limits, changes, and where to get help
Commercial 3
Pricing, plans, and the legal terms of use
Company 6
The organization behind the API
Other 2
Properties that don't map to a standard resource type
← All providers · Data indexed from github.com/api-evangelist/apartments-com · machine-readable index on apis.io