Want to learn Arabic? Klingon? Duolingo turns to the crowd to create new language classes

For the past two years, startup Duolingo has helped people learn new languages while crowdsourcing translations of real-world web content. Now, it’s tapping the crowd for new language classes, too.

To date, the company, which has 10 million users, has released mobile and web classes for six languages. But founder and CEO Luis Von Ahn, who also created ReCAPTCHA, said the startup receives about 50 messages a day from users requesting new languages. In total, he estimates users have asked for the addition of classes for hundreds of new languages.

“We simply cannot add so many by ourselves,” he said. “When we get asked for a language, a fraction say I’m willing to help. We took a cue from that and developed a system that lets the community contribute classes.”

Through the startup’s new Language Incubator, users can apply to add a new language to the site. Duolingo reviews the applications to make sure they’re capable of leading the creation of new classes. And, if approved as a moderator, the startup gives them the blueprint it uses when creating new language classes. For example, it shares a list of the 3,000 words that should be covered, key concepts to include and the order in which material should be taught. From there, moderators can recruit others to help with the content creation.

The most-requested languages are Chinese, Japanese Russian and Arabic. But the startup said people can also add fictional languages like Klingon and Elvish.

Many of the moderators will likely be individuals who believe in what Duolingo is doing and want to support it, Von Ahn said. But he added that organizations interested in preserving indigenous or endangered languages have also indicated interest in using the service.

“It’s people who really care about their language and want to help spread it,” he said.

Duolingo, which is the top-ranked education app in both the iOS (s AAPL) and Android (s GOOG) app stores, has raised more than $18 million from investors including Union Square Ventures and New Enterprise Associates.