Launched in the UK in May 2014, Happn allows people to see who they have crossed paths with in real life. If two people on the platform like each other (by tapping a heart on the other user's profile) then they can start messaging each other.
The French startup, which competes with the likes of Tinder, Bumble, Once, The Inner Circle, and an increasing number of more niche dating apps, said it now has 15 million users worldwide.
Happn said it has a particularly high concentration of users in London, which is its third largest city of users worldwide behind Sao Paolo, Brazil and Buenos Aires, Argentina. Competition for users in London led Bumble to advertise on pavements in East London's Shoreditch without permission.
Happn CEO and cofounder Didier Rappaport told Business Insider last November that Happn had 700,000 users in the UK. At the time, he said Happn was gaining 1.2 million users worldwide every month and that he expected it to catch Tinder in terms of user numbers by 2017.
Tinder hasn't revealed its user numbers publicly but a 2014 estimate guessed it has around 50 million registered users.