There has been "an overwhelmingly positive response" from the supply side, Mr. Enchin said.

"We're always looking for ways to market our clients' parking," said Natasha Richard, business development and marketing co-ordinator at Vinci Park, which operates 2,600 parking lots in 13 countries, including 50 in Toronto.

"We started out with a few test lots with WhereiPark and it took off so well that we've continued to use them."

On the demand side, growth has mostly been organic, Mr. Enchin said.

Diana Shedletsky said she has recommended the app to her entire office after they moved locations earlier this year.

"I found something within a five-minute walk of the office and significantly cheaper than I expected," Ms. Shedletsky said. "It's a very smart idea."

Without WhereiPark, Ms. Shedletsky said she would have relied on word of mouth or driven around until she found a spot, in which case she "definitely" would have ended up paying more.

WhereiPark doesn't charge its customers to list or book a spot, but takes a cut -- between 50% and 100% of the first month's rent -- when a spot is booked. It also gives parking operators the option to use WhereiPark to collect monthly payments, in which case it charges a small additional fee.

"There's no upfront fees or costs to list our spots, so there's no risk or downside if we do not fill the spot," Ms. Richard said.

Mr. Enchin describes WhereiPark as a "pretty lean operation," which includes two employees besides its founders. For the time being, Mr. Enchin and Mr. Zuker are funding the business out of their personal savings, despite a lot of interest from potential investors.

"A surprising number of people are coming up to us and saying, 'Hey, I saw this, how do I invest?' " Mr. Zuker said. "But we decided for now we're not in fundraising mode."

WhereiPark won't reveal its user numbers or demand projections, but parking is a $25-billion business in North America that has attracted major investors such as the Canada Pension Plan Investment Board and the Ontario Teachers’ Pension Plan. Mr. Zuker said he doesn't know of any other companies that connect buyers and sellers of monthly parking spots.

"Industry veterans have told us that we're onto something great and that we're creating value for them," Mr. Enchin said.

"It's amazing to hear people who have been in that game for so long tell us that what we're doing makes a lot of sense and has merits."