Duolingo, the developer behind the popular language-learning app of the same name, has raised another $20 million in funding.
The Series C round was led by Kleiner Perkins and brings Duolingo's total funding to date to $38 million. The plan, according to founder Luis von Ahn, is to use the additional funds to ramp up hiring and improve its existing product to include more analytics, language options and the ability to get certified in a new language.
See also: Breaking the Web's Language Barriers Can Be Fun
"We are already the largest way to learn languages online," von Ahn says. "The goal now is to just completely dominate and I think that we can do that, but for that we need to expand into more languages and add a lot more features."

Duolingo launched its website in mid-2012 and its app a few months later. The app has been praised by a number of publications for its unique model of gamifying the process of learning a new language.
Von Ahn says Duolingo now has 25 million users, helped in part by the fact that the app has been promoted in both the Apple App Store and Google Play. Duolingo is currently adding about 100,000 new users a day.
Though the focus for 2014 is to continue building out the language app, von Ahn says the company may expand to other education services sometime in 2015.
"We may start going to other types of education because our apps have been so successful in education," he says. "We've considered all kinds of things: math, programming, etc. We don't have a specific category we would go to."
Good design breeds great productivity, say the creatives at Behance, who developed The Action Method. That's what sets this pad apart from a regular yellow legal notebook. The visual design reminds you to describe ideas in action steps rather than just jotting them down, in line with Behance's philosophy of "Making Ideas Happen."
Each device has a different form factor, and maintaining consistency takes the stress out of to-do lists and project management. Evernote is a clear winner. You can use it on your desktop or through a smartphone app -- but if you're on a shared computer, you can also sign in through a web browser.
The company has allowed the app to integrate with other tools through IFTTT, further reducing friction.
The built-in chat and real-time editing make Google Docs awesome for collaboration. Even if you're working on your own, it's great to have your documents stored in the cloud and accessible on any web-enabled device. Auto-save ensures that the most recently updated version of a document is always available.
Text docs are most popular, but don't forget that you can create a form and embed it on any site -- which is wonderful for getting feedback from users. The spreadsheet doc is great for a simple budget or keeping track of employee's contact information.
If getting a million emails asking for a high-res version of the company logo drives you crazy, Dropbox is the answer. Files can get lost in inboxes or just be too large to send via email; Dropbox is a perfect solution to keep track of various product design iterations and assets.
Dropbox for Teams allows you to give each member different permissions to collaborate effectively. You can even share large files with partners or the press even if they don't have Dropbox. Check out Dropbox's nifty calculator to see if Dropbox for Teams is a fit for you.
Despite the fancy social networks we see released each day, email is still one of the best ways to connect with customers. The sooner you begin collecting email addresses, the better -- and MailChimp's subscription forms are the way to do it.
MailChimp doesn't begin charging til after you hit 2,000 subscribers. Even if you're not sending out regular newsletters, it's helpful to build your list for when it is time for email outreach. Analytics on campaigns will tell you who opened your email, what they clicked on and more -- it's great feedback into how well you're communicating your product message.
Handwriting activates your brain differently than typing. That might have something to do with the genius breakthroughs that were first scribbled on a napkin.
Paper is an award-winning iPad app developed by FiftyThree that works as an art pad or a journal. It's great for documenting your life or just letting loose with some digital-style fingerpainting. Check out the company's Tumblr to see what people have created.
Uber is neither app nor traditional service, but blends the two. It's a car service with the kind of customer care that wouldn't be possible without mobile phones and GPS technology. It attracts high-end customers with sleek cars and is branded as a private driver rather than a cab service.
But, the convenience is what draws most people in. No money is exchanged with drivers because payments (and tip!) are taken care of on Uber's end. Pricing varies with time and distance, and once you've dropped a pin to request a car, phone notifications let you know how close your driver is. So even if you're standing in the rain, you don't feel totally left out in the cold.
Of all gadgets, the iPad is probably the most ubiquitous. It sort of works as a laptop replacement (but not if you do a lot of coding or design) and is also great for reading blogs or watching videos. Best of all, it's slim, which makes it a great companion for travel or conference-going.
Depending on your use case, there are plenty of accessories, like keyboards or a stylus, that make the iPad work better for you. Not to mention, most entrepreneurs make a habit of staying on top of the latest tech product releases -- and many these days are first released as an iPad app, so it helps to be able to experience these products first-hand.
When you're hopping on and off planes and trains to meet with venture capital firms, you have to travel light. Luckily, a PSP can go everywhere with you. It's great for both business trips and just taking a break. Because sometimes you need to escape for a little bit to rejuvenate your thought process.
IdeaPaint is trendy, and for good reason. It turns any surface into a white board. Depending on the size wall you decide to transform, you get quite a bit of space to draw or mock up ideas. Not surprisingly, this makes the process more collaborative. Plus, IdeaPaint is cost-effective, compared to purchasing whiteboards for the office or home.
The company recently launched a transparent version, which means you can make a dry erase wall without compromising on colors.
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