Have you ever wanted to sell your old items online with people nearby? Well now, there’s an app for that.

5miles, a hyper-local marketplace app using GPS location, offers an easy way for consumers to buy and sell items on their phone. The app was launched in January 2015 and gained five million users in one year with $10 million in transactions in Dallas alone.

Lucas Lu, the app’s founder, graduated from SMU with a doctorate in physics. Lu teamed up with fellow SMU grad James Kuai, 5miles’ chief communications officer, to create the app in 2014. He said his time at SMU prepared him for the data analysis that goes into creating an app.

“When I started at SMU, my major was physics. I did a lot of data analysis and calculations,” Lu said. “I had a lot of training in that and understanding why data looked like that.”

Lu said he got the idea for 5miles after buying a printer off Craigslist. The printer was broken and he could not do anything to fix the situation and ward off scammers.

“I thought, ‘We should solve the problem and make people feel safe when doing transactions on mobile [devices],’” he said.

Mark Brinkerhoff, 5miles chief marketing officer, said the app uses a triple verification process by phone, email and social account so users can be verified.

“Buyers and sellers can rate and review each other based on their experiences so part of it is self-leasing and part of it is community-leasing,” Brinkerhoff said.

The app also uses a private portal to arrange the exchange and a team that reviews items and supports users. Lu said this is how 5miles differs from Craigslist.

“On the backend we monitor the location to make sure the location is close to where your telephone is, he said. “We do a lot of analysis on that to make sure the seller is true and has verified their identity.”

The most popular items in terms of dollar amount and volume are cars, electronics and furniture. Right now, 5miles is testing revenue models on ways to monetize the app in Dallas. They are driving their recent $30 million toward expansion and marketing.

Lu said the ultimate goal for the app is connecting local people with local businesses nationwide.

“This year is really important for us since we plan to expand,” Lu said. “Next year we plan to be nationwide and we may go to new countries.”