“I was thinking about what was out there at the time,” Mr. Simkhai said one afternoon at the Grindr office, a suite of rooms on the ground floor of a nondescript West Hollywood office building.

“Craigslist was so anonymous and explicit,” he said. “And on Craigslist, you have no real identity. It’s just a post. It’s not your face or maybe not even a real ID.”

With Grindr, Mr. Simkhai said: “You can’t change your identity so much. Most dating sites require you to post a face pic and we think a lot about do we force you to post a picture of yourself, rather than a cat or scenery, because those scenery pics really drive me nuts.”

Hanging on a wall behind Mr. Simkhai’s desk is a variety of masks, including one resembling Hannibal Lecter’s face restraint, references to the Grindr logo, which is a mask. Given the historic necessity for gay men to live in concealment, a mask may seem a curious choice of logo, and yet it is not altogether at odds with Mr. Simkhai himself, who though he wears his paradoxes lightly can sometimes seem like two very unalike personalities in the body of one small man.

Close to 40, he appears far younger and has about him the air of an overgrown adolescent. Head of a successful privately held and far-reaching international business, he is so low-key as to be easily be mistaken for a parking attendant. Boyishly handsome, with a toothy smile and a shock of dark hair, he claims to be beset by physical insecurities.

“Grindr made me get fit and go to the gym more, get better abs,” said Mr. Simkhai, who occasionally posts a shirtless photograph on his own profile. “People criticize it for being superficial, but I didn’t invent that in human nature. What Grindr does is makes you raise your game.”