A custom WordPress plugin developed by TheWebStudio.ca to connect real estate websites directly to RESO-certified IDX Web API feeds — delivering live MLS listing search, flexible filtering, and fully branded property displays without relying on third-party IDX widgets or iframe-based solutions.

This project turned raw RESO API data into a structured, on-brand property search experience within WordPress — giving real estate professionals and agencies full control over how listings are retrieved, displayed, and navigated.

The RESO Property Search Widget was built to solve a recurring problem in real estate web development: most IDX solutions are delivered as iframes, external widgets, or subscription-gated platforms that offer little design flexibility, poor theme integration, and no control over the user experience once a visitor leaves the embedded search.

TheWebStudio.ca designed and developed a plugin that connects directly to RESO Web API-certified MLS feeds using OAuth 2.0 or static Bearer token authentication, retrieves live property data directly from the MLS feed, and renders it natively within WordPress using a fully configurable shortcode and template system.

The result is a reusable, professionally architected IDX integration system that supports branded listing displays, multi-profile search configurations, server-side rendered results for SEO, a compact homepage search widget, and a dedicated XML sitemap feed for listing pages — all managed from a structured WordPress admin panel.

Client: Internal Product / Real Estate Agency Application
Agency: TheWebStudio.ca
Scope: WordPress Plugin Development, RESO Web API Integration, Admin UI System, Front-End UX
Platform: WordPress
Stack: PHP, JavaScript, RESO Web API (OData), OAuth 2.0, WordPress shortcode framework, transient caching, native XML sitemap API

Connecting a WordPress site to a live MLS feed through a RESO Web API endpoint introduces significant technical and UX complexity. The plugin needed to handle real-time data retrieval, multiple authentication types, flexible search field configuration, and a responsive front-end — while remaining practical for real estate professionals to manage without developer involvement.

• RESO Web APIs require OAuth 2.0 or Bearer token authentication with proper token caching to avoid rate-limiting
• OData query construction needed to support diverse field types, filter modes, and multi-value selections
• Property metadata schemas vary by MLS provider — the plugin needed dynamic field discovery to remain adaptable
• Most real estate sites need more than one search context (e.g. residential vs. commercial, different city profiles)
• Live API calls on every page load would create performance and quota issues without a structured caching approach
• Search results needed to be crawlable by search engines, not just JavaScript-rendered, to support SEO goals
• Site owners needed a simple homepage search entry point that didn’t require the full search interface on every page

• Build a complete RESO Web API client supporting OAuth 2.0 and Bearer token authentication inside WordPress
• Deliver a fully configurable property search shortcode with listing cards, photo carousels, pagination, and sorting
• Implement a Search Profiles system so a single plugin installation can power multiple distinct search experiences
• Add server-side rendered (SSR) results with progressive JavaScript enhancement for search engine indexability
• Provide a compact Mini Search widget shortcode designed for homepage and landing page placement
• Integrate a dedicated XML sitemap provider to register individual listing detail page URLs with WordPress’s native sitemap system
• Build a practical admin panel with API credential management, field configuration, display controls, and a live API Tester
• Design the system for reuse across multiple real estate client sites with minimal reconfiguration

The API layer was built as a dedicated class handling both OAuth 2.0 Client Credentials and static Bearer token flows. Tokens are cached using WordPress transients, eliminating redundant authentication requests. OData filter construction is handled programmatically from field configuration arrays, supporting equality matches, case-insensitive text contains, range filters, and multi-value picklist selections — producing clean, spec-compliant API queries across different MLS providers.

Rather than hardcoding MLS field schemas, the plugin includes a metadata class that fetches and parses the OData CSDL XML from the provider’s /Property/$metadata endpoint. This gives administrators a live field list from their specific API feed, making the plugin adaptable to different RESO-certified providers without code changes. Metadata results are cached for 24 hours via transients to avoid repeated parsing overhead.

A Search Profiles admin interface was introduced to allow a single plugin installation to power multiple independent search experiences on the same site. Each profile stores its own field configuration — including which fields are shown, their labels, filter modes, autocomplete settings, and multi-select options. Profiles are referenced by slug in the shortcode, making it straightforward to deploy different search contexts for residential, commercial, rental, or geographic segments.

Standard AJAX-driven search results are invisible to search engine crawlers. To address this, the plugin detects reso_* GET parameters on page load and performs a server-side API query, rendering a structured HTML block of matching listings before JavaScript initializes. The JS layer then progressively enhances the experience by auto-submitting the interactive form and replacing the SSR block — giving search engines a crawlable, paginated results page while users get a fast interactive experience.

A dedicated

Listing detail pages needed to be discoverable by search engines independently of the main search interface. A custom sitemap provider class was registered with WordPress’s native sitemap system, generating paginated XML sitemap entries for each listing detail URL. This gave real estate sites a structured pathway for search engines to index individual property pages without any third-party sitemap plugin dependency.

Core RESO API client with OAuth 2.0 and Bearer token authentication. Main