aid: onthemarket url: https://raw.githubusercontent.com/api-evangelist/onthemarket/refs/heads/main/apis.yml name: OnTheMarket kind: company description: >- OnTheMarket is the third-largest residential property portal in the United Kingdom, operating onthemarket.com. It was founded in 2013 by Agents' Mutual Limited as an agent-owned challenger to Rightmove and Zoopla, listed on AIM as OnTheMarket plc, and was acquired outright by CoStar Group in December 2023 for approximately GBP 99 million. In a market with no MLS and no cooperative listing standard, OnTheMarket sits at the demand end of the value chain: consumers search the portal, and listings arrive from member estate agents' CRM systems rather than from a shared data pool. Its API posture is honest and narrow. There is no public developer portal — developer., developers., api. and docs.onthemarket.com do not resolve, and /developers, /api, /docs, /openapi.json, /swagger.json and /api-docs all return 404 on the main site. What does exist is a member-only integration surface: the OnTheMarket Real Time Datafeed (RTDF), a Rightmove-RTDF-compatible feed API served from the live, OnTheMarket-operated host realtime-api.onthemarket.com, used by agency CRM vendors to push listings and pull branch enquiries on behalf of member agents. No machine-readable contract for it is published anywhere; OnTheMarket's developer guide is distributed under agreement, and every path on the host returns 404 to an anonymous caller. There is no RESO Web API or Data Dictionary certification, no OData $metadata document and no Universal Property Identifier anywhere in the stack — RESO is a North American construct and the UK has never adopted it, so "certified but unreachable" does not apply here; there is no certification layer in this market at all. OnTheMarket publishes no open data. The genuinely open UK property layer belongs to the public sector — HM Land Registry Price Paid Data and Ordnance Survey — and none of it comes from the portals. OnTheMarket's own Terms of Use go further than most and expressly forbid automated access to any page other than the home page. accessModel: pricing: paid onboarding: membership-required trial: false try_now: false public: false label: Paid · OnTheMarket agent membership and a data-feed agreement required confidence: high source: - terms-of-use - documentation - probes generated: '2026-07-26' method: manual image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/onthemarket.png tags: - Real Estate - United Kingdom - Property Listings - Property Portal - PropTech - Rentals - Estate Agents - Data Feed - New Homes - Commercial Real Estate created: '2026-07-26' modified: '2026-07-26' specificationVersion: '0.19' apis: - aid: onthemarket:onthemarket-real-time-datafeed-api name: OnTheMarket Real Time Datafeed (RTDF) API description: >- OnTheMarket's member-only feed API for estate-agency CRM software. It is modelled on the Rightmove Real Time Datafeed (RTDF/ADF) specification, with OnTheMarket-specific differences in request and response fields and an "Only With Us" capability for exclusive listings; overseas properties are not supported. The service host realtime-api.onthemarket.com is live and presents an OnTheMarket TLS certificate (subject O=Agents' Mutual Limited, CN=*.onthemarket.com), and the enquiry endpoint /v1/property/getbranchemails is published in third-party CRM vendor setup instructions. OnTheMarket publishes no documentation, no OpenAPI, no Swagger and no OData $metadata for it: every path on the host returns HTTP 404 with an empty body to an anonymous client, and there is no self-service signup. Access requires an existing OnTheMarket agent membership with a data feed in place, arranged through OnTheMarket support — a Rightmove-style RTDF connection using a client certificate over TLS. Listed here as a real but undocumented and member-gated surface, with no machine-readable contract available to harvest. humanURL: https://expert.onthemarket.com/contact-us/ baseURL: https://realtime-api.onthemarket.com/v1 tags: - Data Feed - Property Listings - Leads - Estate Agents properties: - type: Website url: https://expert.onthemarket.com/ - type: Support url: https://expert.onthemarket.com/contact-us/ common: - type: DomainSecurity url: security/onthemarket-domain-security.yml - type: Conformance name: Standards conformance assessment (derived) url: conformance/onthemarket-conformance.yml - type: Lifecycle name: Versioning, deprecation, SLA and status posture url: lifecycle/onthemarket-lifecycle.yml - type: Packages name: Client-library survey (no first-party packages) url: packages/onthemarket-packages.yml - type: LLMsTxt name: API Evangelist-generated llms.txt for OnTheMarket url: llms/onthemarket-llms.txt - type: LLMsTxt name: OnTheMarket Expert llms.txt (published by OnTheMarket, saved verbatim) url: https://expert.onthemarket.com/llms.txt - type: Website url: https://www.onthemarket.com/ - type: About url: https://www.onthemarket.com/about/ - type: TermsOfService url: https://www.onthemarket.com/terms/ - type: PrivacyPolicy name: Privacy notice (redirects to the CoStar Group global privacy notice) url: https://www.onthemarket.com/privacy/ - type: Blog url: https://www.onthemarket.com/content/ - type: BlogRSS url: https://www.onthemarket.com/content/feed/ - type: HelpCenter name: OnTheMarket Expert Help Centre (member-facing) url: https://expert.onthemarket.com/help-centre/ - type: Partners url: https://expert.onthemarket.com/our-partners/ - type: Support url: https://expert.onthemarket.com/contact-us/ - type: SignUp url: https://expert.onthemarket.com/join-us/ - type: Login url: https://expert.onthemarket.com/apps/login - type: GitHubOrganization url: https://github.com/OnTheMarket - type: LinkedIn url: https://www.linkedin.com/company/onthemarket/ - type: ParentCompany url: https://www.costargroup.com/ maintainers: - FN: Kin Lane email: kin@apievangelist.com