I used Lending Tree when I was last shopping for a mortgage. It's a good way to get a lot of brokers to call you in a hurry.
Most of them were sales sharks, of course, but if you've got 8 hours on your hands and can wade through all of the BS, you can get actual quotes out of them. I found about half of them to be at least a point over the going rate, and they pushed hard on why I should go with them. All kinds of garbage about superior service, which is funny since it's literally a bank's money and they're just going to sell your loan right away anyway, no matter how much they claim to the contrary.
But if you take good notes, you can play them against each other and rapidly determine who actually wants to compete for your business and who's just looking for a sucker to scam. I called them all back and gave them the best quote I had received thus far, and every single broker beat that first best quote. Rinse and repeat and only two of them beat the best quote from that round. The last two brokers I had to call back like four times until one of them finally dropped out.
As a side note, I also spoke to my agent's broker but her rate quote was ridiculous. When buying a mortgage, you'll literally save tens of thousands of dollars if you can put up with a few hours of annoying phone calls to get the best deal available to you. It's annoying, but it's also one of the highest hourly wage tasks you'll ever do.