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Popular language learning app Duolingo has raised $30 million in a series F round of funding from Alphabet’s investment arm CapitalG.

This takes Duolingo’s total raised to $138 million and gives it a valuation of $1.5 billion — more than double the valuation at its series E round back in 2017. CapitalG, under its former Google Capital brand, also led Duolingo’s series D round back in 2015, so its decision to return for more of the same four years later is a vote of confidence.

“Duolingo has been adding users and revenue at an impressive pace, continuing to solidify their position as the number one way to learn a language globally,” said CapitalG general partner Laela Sturdy in a press release. “The team has demonstrated that sticking to their mission of providing free education is not only good for the world … it’s also good for business.”

Founded out of Pittsburgh in 2011, Duolingo is a cross-platform app that enables anyone to learn languages for free, though they can also pay $7 each month for a premium service that removes ads, delivers offline access, and more. Through gamification and bite-sized lessons, anyone can learn to read, listen, and speak in most of the world’s prominent languages, and it also supports many niche vernaculars and fictional tongues such as Klingon.

Above: Duolingo: Klingon is here

Duolingo claims 30 million users are actively learning languages on its platform, and it has emerged as one of the most downloaded educational apps globally. Since its last funding round more than two years ago, it has more than doubled its employees from 95 to 200 and has opened additional offices in Seattle, New York, and Beijing. It also now claims annual bookings of $100 million after it launched its premium plan in 2017, a significant increase from the $33 million it drew in last year.

Interestingly, Duolingo also now lays claim to being the first Pittsburgh-based unicorn (startup with a valuation of more than $1 billion). With another $30 million in the bank, it plans to invest in R&D for new products and grow its team around the world.

The online language learning market was reportedly worth $9 billion in 2018, a figure that could rise to more than $20 billion by 2026. Against this backdrop, Duolingo has been investing in AI and machine learning to make lessons more engaging by automatically tailoring them to the individual — similar to the way a human tutor might. The company confirmed that part of its new cash bounty will be used to grow its AI and machine learning capabilities.

“We started Duolingo with the mission of making education free and accessible to everybody, and I’m very proud that we’ve now also built a strong business,” added Duolingo cofounder and CEO Luis von Ahn. “CapitalG has been a valuable partner to Duolingo over the past few years, and we look forward to using this investment to continue our growth and further solidify our position as the most widely used and top-grossing language learning app worldwide.”

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