“Bop Spotter”: Someone Hid a Secret Phone In San Francisco to Track Songs In the Streets

San Francisco's Mission District has a new secret DJ, and it's not spinning decks—it's eavesdropping on every song that drifts through its streets.

There’s a musical spy lurking above San Francisco's Mission District: a solar-powered Android phone hidden on a street pole in an undisclosed location, tirelessly listening to every "bop" it catches below. Tracking the sounds of the 415 like a silent music sleuth, the low-budget contraption is operated by an old Android phone rigged with Shazam and logs an endless playlist of everything it hears.

The curious invention by Riley Walz is no ordinary gadget. Nicknamed the "Bop Spotter," it’s always on, ready to tag every song played in earshot. So far, the eavesdropping device has identified many electronic anthems crossing into its neighborhood orbit, including "Where Are Ü Now" (by Skrillex, Diplo and Justin Bieber) and "Break Free" (by Zedd and Ariana Grande).

You can even track and download the entire playlist to see the music being recorded in real-time. The Bop Spotter's log reveals a genre-blending mix of pop hits, hip-hop throwbacks, reggaeton bangers and dance anthems. With a CSV file downloadable from Walz's website, anyone can tap into the cityscape's sonic diary and imagine they’re walking right through the Mission District's streets.

For Walz, the payoff is more than just capturing the next hit. His favorite moment so far has been clocking the Bill Withers classic "Just the Two of Us" at 3am in, presumably, a moment of pure spontaneity.

Walz says he drew inspiration from urban tech like the police's ShotSpotter, which is designed to triangulate the location of gunshots in dense areas, but his project has a different mission altogether: tracking the city's organic soundtrack. The Bop Spotter and its covert, nonstop DJing gig cost him around $100, he told 404 Media.

"This is culture surveillance. No one notices, no one consents," Walz writes. "But it's not about catching criminals. It's about catching vibes. A constant feed of what’s popping off in real-time."

You can find out more about the Bop Spotter and access its full music log here.