Feeld is a dating app with options that put the Kinsey scale to shame.

If you’re single, you can set up an account stating your preferences and curiosities, as you might with any other service. The app lists 20 possibilities for sexuality alone, including heteroflexible (straight-ish) and homoflexible (gay, for the most part).

But couples and partners can sign up, too, in service of finding a third — or a fourth.

The app was released in 2014 by Dimo Trifonov and Ana Kirova, two graphic designers living in London, as 3nder (pronounced “Thrinder”). They hoped to appeal to individuals and partners looking to join or have threesomes. But after Tinder filed a lawsuit and the company rebranded as Feeld (as in “playing the”), the founders said they welcomed the opportunity to expand the mission of the app.

“Feeld is a platform for alternative dating, for people who are beyond labels,” Ms. Kirova said in an interview. “They can meet each other without the necessity of coming from a very defined place with a very defined requirement.”

According to the company, the majority of Feeld users are between the ages of 26 and 32, and they cluster in major cities: New York, London, São Paulo, Los Angeles and Paris. About 35 percent are on the app with a partner, and 45 percent identify as something other than heterosexual. (Gender options include nonbinary, intersex and two-spirit, as well as gender-nonconforming, genderqueer and gender-questioning.)