If you want to learn a language for free, DuoLingo is a good way to get started. If you stick with it, it will teach you grammar and vocabulary well, but it’s not good at helping you learn to speak it. And as long as you don’t mind learning from a computer and the oddities that come with that, you will make good progress in your new language.
DuoLingo operates by finding text on the internet in your target language and making exercises out of it for you to learn the grammar and vocabulary. You can learn Spanish, Portuguese, Italian, French, German, Dutch, Irish, and Danish (though Dutch, Irish, and Danish are still in beta), and they have another set of languages about to roll out, including Hungarian, Swedish, Turkish, Russian, and Romanian.
The first thing to know about DuoLingo is that you really have to stick with it in order for it to be worth your time. It truly takes daily practice, and after you create your account DuoLingo will spam you with emails to make sure you know that. That said, if you do stick with it, you will make good progress with your grammar and writing. DuoLingo is very proud of a study that found that 34 hours of DuoLingo on average (so a little over about an hour a day for a month) teaches you the same amount as an introductory college language course. However, that study only measured writing and comprehension, not speaking. They recently implemented a speech recognition portion for some of the languages, but at this point it works quite badly. So DuoLingo is best for gaining a good overview of the grammar and structure of a language. If you want to practice your speaking, though, it’s best to find some other resource.
Also, if you’re ok with only learning the grammar and vocabulary, be prepared to be drilled a lot. If you’ve never heard or seen the language before it’s probably good for you, but if you have had any exposure to the language it can seem pretty tedious. It does give you the option to test out, but if you make more than three mistakes in the test it drops you right back at the beginning. That’s the same with any of the lessons– you get a limited number of “lives” (four at the beginning, three a little later, and eventually just one), and once you’ve gone through those you have to start the same lesson over. So be meticulous.
The last oddity about DuoLingo is that it often feels like you’re learning with a computer program. That’s because you are. As mentioned before, DuoLingo operates by finding text on the internet for you to translate, and sometimes that can be a little bizarre. It also reads you the phrases in computer-voice, which can be somewhat disconcerting. But as long as you don’t get weirded out by hearing and translating phrases like “I have kept my fingers,” you’ll do fine.
Overall, DuoLingo is a great way to get started in a language for free. Because of its easy interface and cute graphics, it doesn’t seem like a huge investment to start out. But the thing is, it actually is a big investment of time if you want to actually learn. Otherwise, you’ll just be typing out random phrases.