Ever since Facebook replaced the back-fence kaffeeklatsch, fewer people know their neighbors well, if they even know their names. But a free online platform called Nextdoor is aiming to change that.

Nextdoor allows individual neighborhoods to create private networks on which users can post everything from "looking for a baby sitter for Saturday night" to "Help! My house is on fire."

There are now more than 1,000 neighborhoods across 45 states using Nextdoor, among them three in the Twin Cities area -- Nextdoor Central Neighborhood near Powderhorn Park in Minneapolis, Nextdoor Pleasure Creek in Blaine and Nextdoor Minikahda Vista on the Edina-St. Louis Park border. Dan Cooley, a broker, started the Minikahda network last fall after living in the area for 2 1/2 years.

"It seemed like a simple, intuitive way to get everybody together in the same place, to stay in touch with your neighbors, and only your neighbors," he said.

To keep things legit and strictly private, Nextdoor requires proof of residency by asking for a potential member's street address, then mailing a special code to that address. Nextdoor recommends starting with no more than 100 to 150 homes, but it's also possible to expand or merge with other neighborhoods.

So far, 16 families in the 117-home Minikahda area have signed up. Cooley and his wife, Sharis, just welcomed their third child, and announced it on Nextdoor. Dan has used it to let the 'hood know that a possibly dangerous stray dog was on the loose. A traveling neighbor for whom he did some snow shoveling thanked him on the site, and some neighbors use it to lend and borrow tools.

"I talk with my neighbors more often than I used to," he said. "I definitely feel like it's more of a community now."

For more info, see nextdoor.com.