Close enough to San Francisco that the same map covers both, far enough that the crowd is different. BART puts most of the East Bay inside half an hour.
Map & Mingle shows you roughly where somebody is, never exactly. Coordinates shown to anyone else are snapped to a grid of about 500 feet, so you can judge whether meeting is realistic without anyone being locatable. Looking is free and needs no photo. Everyone is 18 or over.
We publish the real number of people on the map near Oakland on this page. If it is small, it says so. There are no invented profiles and no fake activity notifications on this service.