Comparables & Valuation API and MCP Server: Comparable Properties and Estimated Prices

Deliver evidence-backed comparables and estimated property values into your systems via REST or directly inside AI assistants using the Casafari MCP server.

CASAFARI's Comparables & Valuation API returns comparable properties and an estimated market value for a residential home starting from geographic coordinates, a postal address or, in Spain, a cadastral reference. The comparables draw on four distinct evidence streams: active market listings, past sales, rental history and official registry records. Available through four REST endpoints or as a dedicated MCP tool (https://platform.casafari.com/mcp/comparables) for Claude and ChatGPT, each comparables query consumes 25 usage tokens, while Location Lookup queries remain free of charge.

What the Comparables & Valuation API returns

When assessing residential real estate, a single market estimate without context carries little authority. The Comparables & Valuation API provides a structured payload that combines an estimated market price (or rental value) with the underlying property evidence used to arrive at that figure.

To identify a subject property, you can submit three types of location inputs:

Geographic coordinates: A latitude and longitude point specifying the subject location.
Postal address: A standard street address resolved through our free Location Lookup service.
Cadastral reference (Spain only): A 20-character identifier printed on local property tax bills (IBI) and title deeds (escrituras), searchable officially on the Sede Electrónica del Catastro. You can read more on why the cadastral reference helps a valuation.

For every query, the API delivers up to four tiers of evidence, each tagged with its source and transaction month:

On-market listings: Active or recent asking prices, including time on market and portal sources.
Past sales: Historic asking prices and completed listing histories tracked across agency networks.
Past rentals: Long-term and short-term rental histories used to estimate market rents and gross yields.
Official registry records: Transaction records sourced directly from government tax authorities and property registers.

The response object returns calculated proximity distances, floor areas, historical transaction values and square-metre price metrics, paired with an estimated valuation for the subject property. You can inspect the full request schema in the Comparables & Valuation developer documentation.

Why comparables rather than a black-box AVM?

Automated Valuation Models (AVMs) output a single algorithmic figure. However, credit risk officers, audit committees and chartered surveyors require transparent documentation explaining how that valuation was derived. The RICS Valuation – Global Standards (Red Book), effective 31 January 2025, emphasizes that professional valuations must remain fully audit-traceable and backed by verifiable market evidence.

Comparables provide this audit trail. Each returned property explicitly details its characteristics, list or sale dates, and verifying data sources.

For property professionals familiar with the UK market, HM Land Registry Price Paid Data provides free monthly records of completed sales across England and Wales. CASAFARI fulfills this exact role across its target Southern European markets, integrating official registry data directly alongside live listing metrics within a single API request.

The calculated property estimate serves as an empirical foundation, designed to inform—rather than replace—the professional judgement of valuers and real estate appraisers.

A valuer in Lisbon: from an address to a CMA in an afternoon

Consider an independent valuer instructed by a mortgage lender to evaluate a two-bedroom flat in Lisbon. Relying on broad municipal averages offers limited practical insight. According to INE's local house-price statistics for Q1 2026, the median transaction price across the municipality of Lisbon reached €5,292/m², compared to €5,000/m² in neighbouring Cascais and €4,511/m² in Oeiras. Looking broader, INE's local house-price statistics for Q4 2025 show a national median of €2,198/m² (a 17.5% year-on-year increase). Prime micro-markets in Lisbon, such as Campo de Ourique, trade at substantial premiums to emerging areas like Marvila.

Rather than manually gathering portal data across multiple windows, the valuer passes the property address to the Comparables & Valuation API (or queries Claude directly via the MCP server). Within seconds, the system returns matching active listings, historical sales, and recorded deed figures nearby.

After reviewing the dataset and filtering out unrepresentative entries—following established guidelines on what counts as an outlier among comparables—she reviews the remaining comparables. The underlying dataset can then be compiled into a standardized presentation by following our technical guide on turning comparables into a client-ready CMA report. The mortgage credit committee receives a fully transparent valuation supported by direct transactional evidence.

How to call it: REST, Claude or ChatGPT

Integrating CASAFARI comparables into existing software architectures or AI workflows requires minimal setup.

REST API Integration

To build custom lending portals or CRM tools, start by obtaining an API key:

Sign in to the CASAFARI platform to access the console and generate your credentials.
Execute a Location Lookup request (free) if converting plain text addresses into structured location IDs.
Invoke the core comparables endpoints detailed in our developer documentation to extract matching evidence.

Model Context Protocol (MCP) Integration

For teams utilizing AI assistants, the API is available as an MCP remote server at https://platform.casafari.com/mcp/comparables via Casafari MCP for AI agents.

In Claude Code, execute the following CLI command to attach the server:

claude mcp add --transport http casafari-comparables https://platform.casafari.com/mcp/comparables

Once connected, users can submit conversational prompts directly to Claude or ChatGPT, such as: "Find two-bedroom sold comparables within 500 metres of Rua Garrett, Lisbon, from the last 12 months."

Operational Cost Structure

Location Lookup: Free of charge.
Comparables Execution: 25 usage tokens per query response.

Note: Usage tokens are your account balance for queries, distinct from standard OAuth access tokens used for request authentication.

Who builds on it, and for what

The API supports diverse real estate, banking, and technology operations:

Valuers and Appraisers: Efficiently aggregate verifiable market evidence for formal valuation reports; learn more about CASAFARI's products for real estate appraisers.
Mortgage Lenders & Risk Teams: Automate collateral underwriting and portfolio valuations using official registry data anchors.
Proptech Developers: Power instant valuation tools and rental yield calculators via the CASAFARI Property Data API.
Estate Agents: Generate client comparative market analyses using CASAFARI's Valuation & Market Study product, review our guide on how to value a property with CASAFARI, or direct prospective sellers to our simple online property valuation tool.

To begin testing, create a key on the CASAFARI platform or configure the remote MCP endpoint directly in your workspace.

Frequently asked questions

What is a comparables API, and how is it different from an AVM?

A comparables API supplies explicit property evidence—such as active listings, historical sales, rentals, and registry records—with source metadata and transaction dates to substantiate a property's market value. Conversely, an Automated Valuation Model (AVM) outputs only an algorithmic point estimate without revealing the underlying comparison data. CASAFARI's Comparables & Valuation API delivers both the calculated market estimate and the detailed transaction evidence required for audit compliance.

Can I get comparable properties from a cadastral reference?

Yes, for properties located in Spain. Submitting a 20-character Spanish referencia catastral allows the API to automatically resolve the subject property's characteristics and location. For properties in other jurisdictions, queries can be initiated using standard postal addresses or geographic coordinates.

Does the Comparables & Valuation API include actual sold prices from the registry?

Yes, official registry records form one of the four main evidence types returned by the API, alongside current active listings, historic property listings, and rental records. This provides verified deed prices alongside market asking prices within a unified request payload.

How do I use CASAFARI Comparables in Claude or ChatGPT?

You can connect the endpoint https://platform.casafari.com/mcp/comparables as a remote MCP server. For Claude Code, run the command claude mcp add --transport http casafari-comparables https://platform.casafari.com/mcp/comparables. Once connected, you can request property comparables and rent estimates using natural language prompts.

How much does a property valuation API call cost?

Each comparables query costs 25 usage tokens from your account subscription plan. Address queries processed via the Location Lookup endpoint are completely free of charge. Usage tokens are your account balance for dataset queries, separate from OAuth access tokens used to authenticate requests.

Which countries does the Comparables & Valuation API cover?

Coverage spans CASAFARI's primary European real estate markets, with specific data features—such as Spanish cadastral reference resolution or official registry price streams—available depending on local market infrastructure. Please consult our guide on where CASAFARI data is available for current regional availability details.