Privately owned public spaces are maintained by companies but free for everyone to use. But sometimes they can be a little hard to find. A new app wants to let you in on some of San Francisco’s secret parks.

If you live in a big city, chances are pretty high that you’re surrounded by privately owned public spaces (known as POPS or POPOS, depending on where you live). Some of them–like New York City’s Zuccotti Park–are well-known. But many are hard to find if you don’t know where to look. SF POPOS, the winning app in the recent DiscoverSF hackathon, is an attempt to curate San Francisco’s 68 POPOS, pointing out the ones that are worth a visit.

A team of 10 people–including a design professor, a UX designer from Google, and a data worker from Pivotal Labs–created the app during the hackathon, which challenged participants to use location-aware technology to help people discover the city and support the local economy.

“The intent was to pull people away from the commercial touristy areas like Union Square and the waterfront and into the nooks and crannies that we have here in San Francisco,” explains Bronwyn Agrios, Business Development Lead for Esri in San Francisco.

SF POPOS grew out of team leader Wendy Fong’s prior interest in POPOS. “The POPOS idea was something that my collaborator and I had wanted to do, thinking of ideas of how to explore San Francisco, what’s already here that’s underexplored,” says Fong. Along with her collaborator (and fellow team member) Lily Chandrasekher, Fong is set to discuss POPOS at an Urban Tech SF meetup in mid-May.

The app is still in the early stages, but the basic idea is to have a curated map of POPOS in the city, with rankings for each space based on amenities (i.e. whether it’s quiet, shielded from weather, etc.). “The app would highlight excellent POPOS and using Esri technology, it would have geotriggers when walking around telling you there’s another POPOS half a block away but on the rooftop,” says Fong.

The SF POPOS app draws on an existing list of POPOS put together by the San Francisco Planning and Urban Research Association (SPUR). But that list, which also is available as an app, doesn’t curate based on POPOS quality–so you could end up being led to a tiny bench adorned with a potted plant when you’re looking for a lush urban garden.

Fong and her team, now reduced to four people, hope to have the app available by mid-June. It’s a goal that will be aided by their grand prize winnings: access to a co-working space, mentoring, and $1000 in Amazon Web Services credits. The group also won the Esri award of $2,000 plus $250 inEsri credits.

The hackathon was organized by San Francisco Travel, Gray Area Foundation for the Arts, and the Mayor’s Office of Civic Innovation. Airbnb and Esri were the headlining sponsors.

Eventually, Fong wants to move the app beyond just POPOS; they tend to be clustered in San Francisco’s financial district, while other outdoor spaces like parklets, playgrounds, community gardens, and stairways (there are hundreds) are located elsewhere in the city. “We want to add on other free and cool stuff in San Francisco,” says Fong.