Client Background
A real estate agency based in Spain approached us with approximately 750 property listings stored in a multi-agency property database. The agency already had several XML feeds but needed a new custom XML feed for a German property portal with very specific technical and data requirements.
The client wanted the feed to follow the receiving portal’s specification precisely rather than simply exporting the existing property data.
The Challenge
The main challenge was creating an XML feed that could:
- Retrieve property information from the client’s external property database.
- Transform the available property data into the required XML structure.
- Follow the receiving portal’s exact XML specification.
- Support the required API-based delivery process.
- Work independently of the client’s main website.
The client initially shared their website, but after reviewing the requirements, it became clear that the primary data source was Resales Online, rather than the agency’s WordPress or website content.
This distinction was important because the XML feed did not need to be generated from the agency’s public website. Instead, the integration needed to work with the external property database and the receiving portal’s requirements.
Understanding the Data Source
The client’s properties were maintained through the Resales Online network. The project therefore required access to the relevant property database rather than relying on the agency website.
After discussing the architecture with the client, we clarified that website access was not required. Instead, the integration would use the appropriate database/API access and a hosting environment capable of running the PHP-based conversion script.
This helped simplify the implementation and avoided unnecessary changes to the client’s existing website.
German Portal Requirements
The receiving company provided technical specifications explaining that XML data had to be submitted through its REST API according to its own XML specification.
The client supplied the technical documentation for the receiving platform, including information about its Import API and Import/Export API. The receiving company also indicated that use of the API was subject to its own service requirements and fees.
This meant the project was more than simply producing an XML file. The feed had to be structured and prepared in a way compatible with the receiving portal’s technical requirements.
API Access and Authentication
During implementation, it became necessary to obtain the appropriate API credentials from the receiving platform.
The client was guided through the API permission process and the relevant self-service area for generating API credentials. When necessary, the client also provided account access so that the integration work could proceed.
Authentication was coordinated with the client because the platform required additional verification during login. The client provided the required verification code while the integration was being configured.
Solution
The solution involved creating a custom XML feed specifically around the client’s external property data source and the receiving portal’s requirements.
The general workflow was:
Property Database → Data Retrieval → Data Transformation → Custom XML Generation → Portal/API Delivery
The approach avoided modifying the client’s main website and instead focused on the data integration layer.
A separate PHP-capable hosting environment could be used to execute the conversion script, allowing the feed generation process to operate independently from the public-facing real estate website.
Project Delivery
The initial project was agreed including revisions and source code.
The project required communication between three important components:
- The real estate agency
- The external property database
- The receiving property portal
This made requirement clarification particularly important before development began.
A Successful Follow-Up Project
The relationship continued after the initial XML feed project.
On March 17, 2025, the same client returned with another requirement: an XML feed for Idealista, a Spanish property portal.
The client explained that Idealista required the feed developer to contact them directly to obtain the XML feed specification. The new feed was expected to be similar to the previous integration, but without the translation requirement used for the earlier project.
A new custom offer was subsequently prepared to develop a feed specifically for Idealista.
Key Lessons
1. Identify the Real Data Source First
A client’s public website is not necessarily the source of truth for a real estate feed.
In this project, the agency website was initially shared, but the actual property data was maintained through an external property database. Identifying this early prevented unnecessary work on the website.
2. Follow the Receiving Portal’s Specification
International property portals often have their own XML structures, required fields, APIs and authentication procedures.
A successful feed therefore needs to be designed around the destination portal’s specification, not simply around the source database.
3. Separate Website Development From Feed Integration
Because the client’s website was not required for this integration, the feed could be developed independently.
This approach reduces the risk of interfering with an existing production website and makes the integration easier to maintain.
4. API Credentials Are Part of the Integration
XML feed development can involve more than XML formatting. When the destination platform requires REST API submission, authentication and API permissions also become part of the technical workflow.
5. A Good Integration Can Lead to Repeat Business
One of the strongest outcomes of this project was the client’s return for another XML feed shortly afterward.
The second request for an Idealista feed demonstrated that successful completion of one portal integration can establish trust for additional international property-feed projects.
Conclusion
This project demonstrates how a custom real estate XML feed can connect an external property database with an international property portal without requiring changes to the agency’s main website.
The key was understanding the actual data source, reviewing the destination portal’s technical requirements, obtaining the necessary API access, and building the feed around the receiving platform’s specification.
The subsequent Idealista request from the same client further demonstrated the value of delivering a practical, portal-specific XML integration that can be extended to additional property platforms.
Project Type: Custom Real Estate XML Feed
Data Source: External Multi-Agency Property Database
Integration: Custom XML + REST API
Follow-Up: Idealista XML Feed Integration