More than 500 people have already signed up to test drive Chicago’s pay-by-phone parking meter app.

The free app went live on Tuesday, kicking off a pilot program that give motorists the option of paying for public parking spots by phone in the West Loop from Madison to Monroe and Halsted to Racine. That area makes up 279 metered spots.

The pilot program is expected to last up to 3 weeks before expanding to all 36,000 meters in the coming months.

To take advantage of the pay-by-phone system, customers must first set up an account via parkchicago.com and link it to a major credit card or debit card.

After finding a parking spot, drivers then input a zone number, which is listed on street signs and — the first time they use the app — their credit card information and a license plate. The app will save your information for future purchases. One of the perks: When you have 10 minutes left, it will send an alert to let you know either to jet back to your car, or pay more.

Drivers are charged a 35-cent so-called “convenience fee” for using the app for parking under two hours.

Some drivers who parked in the West Loop on Tuesday said they simply hadn’t installed the app yet. Others said they didn’t want to pay the 35-cent fee.

“I’m not using it because it’s additional money to pay for parking that’s already expensive,” said Kristen Szabla, 31, of the West Loop.

Szabla said she often parks on Madison Street to run errands. Her nanny takes her home garage spot during the day.

“I always have to park for under two hours,” Szabla said. “It’s not worth it to me. I’d rather just walk to the machine.”

Email: tsfondeles@suntimes.com

Twitter: @TinaSfon