Not long ago, after Alexandra Amin, an assistant at Warner Brothers, broke up with an agent she had been dating for a year, her friend told her about a new, free, female-friendly social networking app that lets women anonymously review men who are their Facebook friends.

“She was like, ‘He’s so crazy, you should rate him on Lulu,’ ” said Ms. Amin, 29, who lives in Los Angeles. Ms. Amin gave the ex hashtags including #NeverSleepsOver and #FriendZone. He scored a 6.9 out of 10, which, she admitted, was “lower than he actually deserves.”

On Lulu, women can rate men in categories — ex-boyfriend, crush, together, hooked-up, friend or relative — with a multiple-choice quiz. Women, their gender verified by their Facebook logins, add pink hashtags to a man’s profile ranging from the good (#KinkyInTheRightWays) to the bad (#NeverSleepsOver) to the ugly (#PornEducated). The hashtags are used to calculate a score generated by Lulu, ranging from 1 to 10, that appears under the man’s profile picture. (The company’s spokeswoman declined to explain the ratings algorithm.) Men can add hashtags, which appear in blue, but these are not factored into their overall score.

Since it was started last year by Alexandra Chong, who has a law degree from the London School of Economics, the service has provided a sort of “Take Back the Internet” moment for young women who have come of age in an era of revenge porn and anonymous, possibly ominous suitors. “The thing that drew me to Lulu was that dating without a reference is the scariest thing you can do,” said Erin Foster, 31, an actress and writer. “Meeting someone out in the world when you’re not in school or don’t work with each other or have mutual friends — you have no idea what you’re getting yourself into.”