I stand by my comment that the Seattle market is unusual, with two local firms dominating over the national firms.
The reason Windermere doesn't participate on Realtor.com is probably that they created an exclusive arrangement with either Trulia or Zillow a few years back. That may still be in effect.
For most other firms it's on an office by office basis where their listings get fed. I'd heard the NWMLS was going to change that, but I've not seen anything come of that yet.
I much prefer the various agency websites, although realtor.com is superior to most national websites. Odd that Windermere doesn't participate there though.
My question still remains re Trulia & Zillow. What do they add to the knowledge base? It seems they are just trying to generate a need and income for themselves, while all the information one could need is available at cbbain.com, redfin, etal.
I had to laugh at the John L Scott "domination" comment. They sure have lost a lot of ground over the past few years. Are they even number 4 in ranking? They do have a good app though.
As to Realtor.com, I think they are bigger (more popular) nationally than locally. It's sort of like how in the Seattle area John L. Scott and Winderemere (local firms) dominate, where nationally firms like Century 21 or Prudential dominate. Also, in many areas the MLS is owned by a Realtor organization, but that's not true here. So Seattle is a bit different.
My friend Kary is right. These sites are not updated from the MLS. The most current information like this will come from a local agent who can help you. The market is crazy right now and not having the most up to date data can cost you money.