The MLS is the source; Zillow and the other portals show a syndicated copy of it. When an agent lists a home, it goes into the local MLS and then feeds out to consumer sites like Zillow and Redfin. That copy step creates the gaps: - Lag. New listings and status changes can take minutes to hours to appear, so a home can still show active on a portal when it's already pending. - Missing homes. Feeds occasionally break, and some brokerages choose not to syndicate certain listings to portals they view as competitors, so a portal-only search can miss homes entirely. A live MLS search set up through your own agent avoids all of that. You see everything, sooner, with accurate status. One practical warning. The contact button on those portals frequently does not reach the actual listing agent. The platform often sells your click as a lead to some other local agent, who then contacts you, which creates confusion at showings about who represents whom. When a listing catches your eye, send it straight to your own agent and let them pull the real MLS detail and set the showing.