What is IDX?
IDX is an acronym for Internet Data Exchange. IDX is the policy instituted by the National Association of Realtors (NAR) to govern how MLS member participants can display active MLS listing information on their websites. In simple terms, IDX is the means of extracting the data from a Multiple Listing Service and delivering it to a website for public consumption. IDX is sometimes called Broker Reciprocity or IDD.
NALMLS IDX Listing Rule
A Participant shall cause any listing that is displayed on his or her website to identify the name of the listing firm and optionally the listing broker or agent in a readily visible color, in a reasonably prominent location, and in typeface not smaller than the median typeface used in the display of listing data.
Why would I want to let someone else display my listings on their website?
Think of it as free advertising. The more exposure for your listings, brand, and name the better! The more places your listings show up, the faster they are likely to sell. The bottom line is that no one gets paid until the property closes. The Internet has taken a once closed MLS system and opened it up for consumers to make faster and better informed buying/selling decisions. IDX opened the door for free advertising on tens of thousands of websites.
Broker Reciprocity isn’t for me. How can I opt-out?
Brokers (and supporting Agents) who decide not to participate in Broker Reciprocity may submit the opt-out form provided by their local board/MLS. However, opting-out may not be a great idea since your listings, brand, and name will not be displayed across the Internet. Opting out will greatly decrease exposure for your listings, and in our opinion, should be seriously reconsidered. Furthermore, opting-out will decrease the ability of getting the benefit of this powerful marketing tool, which will decrease sales.
Does the IDX data contain any confidential information?
No. The IDX data fields available for display to the public are approved by the board/MLS and do not contain confidential information.
– Excerpts from NalMls IDX agreement and IDX Broker website FAQ