A San Francisco startup is betting that would-be tenants will jump at the chance to bid against other renters in order to secure an apartment in the Bay Area's superheated rental market.

Rentberry, an online price auction tool for long-term property rentals, aims to compete with Craigslist and other "Stone Age" rental services.

"Essentially, we offer a more efficient and transparent application process which has the elements of bidding and an auction," said CEO Alex Lubinsky.

As in an eBay auction, tenants would be able to see how many people are competing for the property and what the highest offer currently is. They can make multiple offers before the bidding ends, but landlords would not be compelled to accept the highest bid. For example, they might consider a higher-quality bidder with a lower offer more suitable.

The service, which plans to launch Tuesday in the Bay Area and New York, offers free listings for landlords. Lubinsky said hundreds have already signed up.

Rentberry intends to charge tenants a flat fee of $25 when the agreement is signed. After the business is established in six months or so, Rentberry may require landlords to make monthly payments of one quarter of the extra rental income that the service generated for them.

Let's say a property that was listed for $2,000 a month was auctioned off for $2,075. The landlord would have to pay Rentberry 25 percent of the $75 difference ($18.75) every month for as long as the tenant keeps the apartment.

So why would any apartment seeker struggling with the Bay Area's exorbitant rents — the median rent for a 1-bedroom apartment in San Francisco was about $3,100 per month in February — want to take on potentially more costs incurred by bidding up a rental?

Rentberry estimates that in hot markets like the Bay Area, the average tenant will save 7-10 hours searching for a place and at least $400 in rental application fees. And they won't pay anything for the service unless they sign a rental agreement.

Lubinsky explained that landlords advertising on Rentberry would hold an open house where they can meet and vet prospective tenants, who would be instructed to file applications via the service's platform in what the company calls a "fully closed loop application process."

Credit reports and scores, and background checks would be made free to applicants. Would-be tenants can then submit a bid on the property based on how much they're willing to spend and what their competition is bidding. The length of the bidding process would be up to the landlord.

Winning bidders accepted by the landlord would sign the rental agreement and pay rent and security deposits online through Rentberry.

Leases must be at least six-months and can be as long as two years. The company will not offer short Airbnb-type vacation rentals, Lubinsky said.

Landlords participating in Rentberry's application process can expect to see rental income increases of 5 percent on average, Lubinsky said, based on the company's research of Bay Area real estate metrics.

Some will say the last thing the San Francisco rental market needs is a middleman taking his slice when ordinary people are being priced out every day.

But Lubinsky sees it as a supply-and-demand issue. Why should a landlord who may have paid millions for a rental property not be allowed to maximize rents in order to defray the cost of his investment? he argues.

In addition, bids over asking are routinely received for San Francisco apartments, but competing tenants may not know they've been outbid and therefore do not submit counter offers. Rentberry's auction model makes the whole process more transparent, Lubinsky says.

Lubinsky says property managers, who naturally are looking to expand their cut while enhancing rents for their owners, have been especially receptive to Rentberry.

The company's auction model not only allows prospective tenants to outbid offers, but underbid asking prices in slow markets where landlords are looking to fill vacancies faster. Lubinsky says Rentberry plans to expand in two of those lagging markets — Dallas and Houston — in a few months.

Unfortunately for renters here, no market slowing is expected in the Bay Area anytime soon.