RESO Web API

The RESO Web API is the real estate industry’s current standard for transporting listing data between an MLS and the software that consumes it. Published by the Real Estate Standards Organization, it replaced the aging RETS protocol and pairs with the RESO Data Dictionary, which standardizes what fields are called across markets. When your website shows a listing minutes after a status change, this is the pipe it travelled through.

How it shows up in Canada

Every major Canadian feed an agent’s website depends on now speaks it. TRREB distributes through a RESO Web API platform under PropTx data agreements. The Greater Vancouver tri-board system delivers its combined feed the same way. Even CREA’s DDF, the national syndication channel, moved onto the standard. Under the hood it is an OData-style query interface: a registered vendor authenticates, requests changed records since its last checkpoint, and replicates them into its own database — which is why well-built sites serve listings from their own infrastructure rather than querying the board live on every page view.

Why it matters for your website

You will never touch the API, but its quality ceiling is your website’s quality ceiling. Sync cadence, photo handling, field coverage, and status accuracy all come down to how well the platform drives the standard — and boards audit that, with real consequences for vendors who fall behind. This is one of the honest ways to evaluate a provider: ask whether they are a registered vendor consuming the board feed first-hand or reselling someone else’s integration. BrokerFold pulls board feeds directly as a registered vendor; the board-specific pictures are on TRREB IDX websites and GVR IDX websites.

Common confusions

The Web API and the Data Dictionary are different things: one moves the data, the other names it, and a board can adopt either without the other. RESO itself is a standards body, not a data source — the licence to access a feed still comes from your board, through the usual IDX and VOW agreements. And “RESO certified” on a vendor’s site describes technical capability, not permission: certification without a board agreement displays nothing. The two credentials answer different questions — one whether a vendor can move the data, the other whether it may.