It was at the local bakery that Geraldine Biebuyck saw a note with a number for the girl who would became her family's babysitter. Not a very 21st-century way of doing things, Biebuyck thought - a thought she shared with her friend and fellow working mother Donatienne van Houtryve.

"We kept saying there should be an app for this, and couldn't believe that none already existed," Biebuyck said. "Then, one day, Donatienne said: 'Nobody else is doing it, so let's just do it ourselves.'"

In November, Biebuyck and van Houtryve launched airBsit, and 22,000 users across Belgium have downloaded it since - parents and babysitters alike. The Brussels newspaper Le Soir nominated the women the Belgian capital's citizens of the year.

'A great demand'

Like many other apps, airBsit works by helping match supply to demand. Parents can see which babysitters have previously worked for friends, they can put in a request for their favorite sitters at any given time, and they can enter the hourly rate they are prepared to pay. The babysitters receive a notification and can accept or refuse the job in just a few clicks.

"Everybody has a smartphone," Biebuyck said - and that's why airBsit's services are app-only

Though the app can be downloaded for free, parents pay airBsit 25 percent of the sitter's hourly rate. So, if a babysitter requested the commonly paid rate of 8 euros ($7.10) per hour, parents would pay a fee of 2 euros to the app for brokering the transaction.

In Belgium, a relatively high number of mothers work: 72 percent, according to figures from the Organisation for Economic Co-operation and Development. In the the United Kingdom, it is 66 percent, and in Germany 69 percent. What's more, many work full time. About 40 percent of households with children pursue what the OECD calls the "full-time dual earning" model, contrasted with roughly 20 percent in Germany.

"Families need babysitters to pick up children at day care or school and take care of them until the parents come home from work," said Dominique Leconte, who is charge of babysitting services at the parental organization Ligue des Familles.

"There is also a great demand for babysitters to help families as early as 4 o'clock in the morning to help get the kids ready and drop them off at day care or school while the parents are already on their way to work," Leconte said.

Very 21st-century

Biebuyck and van Houtryve knew all too well the search for someone trustworthy to take care of their kids. They had consulted postings at the bakery and the supermarket, checked in on groups on social media, and asked friends. These were tools that worked, but the women found them cumbersome.

A newspaper nominated Biebuyck (left) and van Houtryve citizens of the year

"We wanted to come up with something that makes this process quick, efficient and simple," Biebuyck said. "But the basic idea was also that people share babysitters with their friends."

AirBsit divides babysitters into three groups: those with whom you have worked before, those friends have used and those who live around the corner.

That's a feature Pierre likes. He and his wife have four children, both work full time, and mostly ask nieces and nephews to babysit when the need arises. "But I like the idea of having babysitters short-listed on the app on the basis of them having worked for my friends," Pierre said.

"I also like the work flow of it," Pierre said. "Normally, you have to ask one babysitter after the other whether he or she is available. Via the app, I can do this much more efficiently."

No security?

Leconte, of Ligue des Familles, feels, that one thing is missing from airBsit. "These kinds of apps merely help in terms of supply meeting demand," she said, "but they don't offer any security."

The membership-based Ligue vets and trains babysitters before allowing them to offer their services on the organization's website.

"At the moment, we don't do any check," Biebuyck said, adding that airBsit might introduce some training for babysitters in the future.

For father of four Pierre, though, that's not even necessary. "The fact that the app uses my friends or contacts as a point of reference is enough of an endorsement for me," he said.