Trying to park a car in a big city can be a nightmare, and Paris, the City of Light, is no exception.

Statistics indicate that at any one time, a third of the traffic in Paris consists of drivers desperately looking for a spot, while more than 120,000 private spaces belonging to businesses and residents sit empty.

After Mr William Rosenfeld spent 40 minutes one night trying to park at a friend's place with a crying baby in the car, he called to cancel, and his friend told him about private parking lots used only in the day. It was a revelation, he said. "That very night, our project was put on paper."

Last year, Mr Rosenfeld and another friend Fabrice Marguerie founded a free mobile phone app called Zenpark.

Subscribers use the app or website to search for an empty spot in a network of formerly unavailable lots and garages. Parking is charged by the minute.

In less than two years, the project has saved its customers in the Paris region 15,000 hours, 200,000km, US$40,000 (S$50,730) of fuel, and 25 tonnes of CO2 emissions - not to mention the stress of driving around aimlessly with a wailing child.

DANIELLE KITCHINGMAN-ROY/SPARKNEWS