If you have ever tried to set up an MLS feed for your realtor website, you have probably hit a wall of acronyms. IDX, VOW, AD-A, RETS, RESO, AMPRE, the alphabet soup is genuinely overwhelming. Most realtors give up and let their brokerage's stock website handle listings, missing out on the SEO advantage of having listings on their own domain.
Here is the plain English version of what each one is, what it lets you display, and who needs it.
IDX: the public listings feed
IDX stands for Internet Data Exchange. It is the most common feed type and the one most realtors actually need. IDX gives you a license to display the active listings from your local board on your own website, with two important caveats: you only show listings that are currently for sale (not sold history), and you must give credit to the listing agent and brokerage.
For most realtors, IDX is enough. It powers the listings page on your site. It refreshes as new homes hit the market. The public sees the same listings they would see on Realtor.ca, just on your domain and with your branding.
IDX listings are public. Anyone can view them on your site without logging in. That is by design. The board wants the listings broadly visible.
VOW: the registered user feed
VOW stands for Virtual Office Website. It is IDX's bigger sibling. VOW gives you the same active listings, but adds sold price history (in markets where sold data is shared, which is most of Canada now), days on market, listing history, and more granular fields.
The catch: VOW data can only be shown to "registered consumers". The visitor has to create an account on your site and agree to a brokerage relationship before they can see VOW level data. This is meant to enforce the broker consumer relationship that traditional real estate is built on.
VOW is useful for higher intent buyers. A casual browser sees IDX. A serious buyer who registers gets the full data. The registration gate also doubles as a lead capture mechanism, which is one of the biggest reasons agents enable VOW.
AD-A: the agent's own listings
AD-A stands for Agent Data Access (the exact name varies slightly by board). It is the feed of your own listings, the ones where you are the listing agent. AD-A gives you the most permissive access to your own data, including everything you uploaded in MLS plus the historical record of price changes, showings, and so on.
You always have rights to your own listings, no special agreement required. AD-A is more about clean technical access to your data than about permissions.
The data flow in 2026
Most Canadian boards moved to the RESO Web API standard between 2020 and 2024. The old RETS protocol still exists in places but is being phased out. RESO Web API is a modern, well documented REST API that any modern developer can consume.
TRREB specifically uses a vendor called AMPRE (query.ampre.ca). AMPRE handles authentication, rate limiting, and the actual API. To get a token, you need to do two things: be a TRREB member in good standing, and authorize a "syndication recipient" through your TRREB portal. Charcom is an authorized recipient, so you authorize us through the portal and a token gets generated.
What you actually need
For a single agent website, this is the practical setup.
Minimum: IDX. This gets your listings page populated, your active inventory visible, and your SEO benefit of having listings on your own domain. Most agents stop here.
Better: IDX plus AD-A. AD-A gives you the cleanest possible data on your own listings, which matters if you have feature listings you want to showcase with full media galleries.
Best: IDX, AD-A, and VOW. VOW adds the registered user gate which doubles as a lead magnet. The sold price history alone justifies the extra setup work for any agent who works with serious buyers.
The bureaucratic reality
Setting up any of these requires three things: a membership in good standing with your board, a "data sharing agreement" signed with your brokerage (most brokerages have a standing one), and a token generation through your board's vendor portal.
The bureaucratic friction varies by board. TRREB is reasonably modern. Some smaller boards still require physical paperwork. The good news is that once you have done the setup, it stays in place. The bad news is that the first setup can take anywhere from one day to three weeks depending on your board's responsiveness.
If you are not sure where to start, just enable IDX with TRREB. That covers 80% of the use cases at 20% of the work.