“Bubbles are for Bathtubs.”

The statement stretches confidently across the top of the Web site Condoflip.com, a new online marketplace for buying and selling condominium units under development. And while the word “flip” may have negative connotations to the real estate community, Condoflip owner Mark Zilbert said he hopes his site will bring developers, buyers, and sellers together to strengthen the market and turn the word flip into a positive one.

“The spirit of Condoflip is not to take advantage of the marketplace,” Mr. Zilbert said. “It’s about working with other developers and brokers to keep the market healthy. My goal is to prevent a bubble.”

Condoflip is starting out marketing properties in Miami, and plans to expand to cities throughout North America, including New York.

Mr. Zilbert said he was motivated to create the site when he saw that the rapid growth of condos in Miami was threatening to lead to an oversupply, His plan is for Condoflip to expose all the new condos to a much larger market of potential buyers, to keep properties selling.

“A bubble comes out of the tens of thousands of sellers who can’t close,” he said.

Leonard Steinberg, a real estate broker who specializes in luxury apartments at Douglas Elliman, said the site came across to him as a discount brokerage.

“A lot of real estate companies already offer what the site offers, which is exposure,” Mr. Steinberg said. “Flipping is a nasty word for reselling, and reselling can be done by a professional real estate broker.”