Grindr has more than 5 million users

"It is easy to write off Grindr — a location-based dating application for gay men — as a hookup application because, well, that is what it is.
But the company, which is approaching its fourth anniversary, has amassed more than five million users who spend on average 90 minutes each day using the application. Billions of messages fly across the service every year, and 76 percent of the company’s revenue comes from money generated by Grindr users who fork over cash for the service’s premium features."

Source:  New York Times, 8th March 2013